fix(backups,files): auto-backups rejected by validator; trip file download broken after cookie migration

Fixes #773: isValidBackupFilename regex anchored to ^backup- rejected all
auto-backup-* filenames, causing 400 on download/restore/delete. Broadened
to ^(?:auto-)?backup-.

Fixes #774: three regressions in the trip Files tab —
- openFile import shadowed by a local function of the same name inside
  FileManager; PDF preview modal was calling the local with a URL string,
  corrupting state and crashing on the second click (mime_type read on
  undefined). Fixed by aliasing the import as openFileUrl.
- GET /:id/download used a bespoke authenticateDownload that checked only
  Bearer header and ?token= query param, ignoring the trek_session cookie.
  After the JWT-to-cookie migration the client sends cookies only, so every
  download silently 401-ed. Extended authenticateDownload to accept req and
  check cookie → Bearer → query token in priority order.
- files.download and files.openError translation keys were missing from all
  15 locale files; t() was returning the raw key as a truthy string,
  defeating the || 'Download' fallback.

client/src/components/Files/FileManager.tsx

@@ -10,7 +10,7 @@ import { useCanDo } from '../../store/permissionsStore'
 import { useTripStore } from '../../store/tripStore'
 
 import { getAuthUrl } from '../../api/authUrl'
-import { downloadFile, openFile } from '../../utils/fileDownload'
+import { downloadFile, openFile as openFileUrl } from '../../utils/fileDownload'
 
 function isImage(mimeType) {
   if (!mimeType) return false
@@ -113,7 +113,7 @@ function ImageLightbox({ files, initialIndex, onClose }: ImageLightboxProps) {
         </span>
         <div style={{ display: 'flex', gap: 8, flexShrink: 0 }}>
           <button
-            onClick={() => openFile(file.url).catch(() => {})}
+            onClick={() => openFileUrl(file.url, file.original_name).catch(() => {})}
             style={{ background: 'none', border: 'none', cursor: 'pointer', color: 'rgba(255,255,255,0.7)', display: 'flex', padding: 4 }}
             title={t('files.openTab')}>
             <ExternalLink size={16} />
@@ -743,7 +743,7 @@ export default function FileManager({ files = [], onUpload, onDelete, onUpdate,
               <span style={{ fontSize: 13, fontWeight: 600, color: 'var(--text-primary)', overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap', flex: 1 }}>{previewFile.original_name}</span>
               <div style={{ display: 'flex', alignItems: 'center', gap: 8, flexShrink: 0 }}>
                 <button
-                  onClick={() => openFile(previewFile.url).catch(() => {})}
+                  onClick={() => openFileUrl(previewFile.url, previewFile.original_name).catch(() => toast.error(t('files.openError')))}
                   style={{ display: 'flex', alignItems: 'center', gap: 4, fontSize: 12, color: 'var(--text-muted)', background: 'none', border: 'none', cursor: 'pointer', textDecoration: 'none', padding: '4px 8px', borderRadius: 6, transition: 'color 0.15s' }}
                   onMouseEnter={e => (e.currentTarget as HTMLElement).style.color = 'var(--text-primary)'}
                   onMouseLeave={e => (e.currentTarget as HTMLElement).style.color = 'var(--text-muted)'}>
@@ -771,7 +771,7 @@ export default function FileManager({ files = [], onUpload, onDelete, onUpdate,
               title={previewFile.original_name}
             >
               <p style={{ padding: 24, textAlign: 'center', color: 'var(--text-muted)' }}>
-                <button onClick={() => openFile(previewFile.url).catch(() => {})} style={{ color: 'var(--text-primary)', textDecoration: 'underline', background: 'none', border: 'none', cursor: 'pointer', font: 'inherit' }}>{t('files.downloadPdf')}</button>
+                <button onClick={() => openFileUrl(previewFile.url, previewFile.original_name).catch(() => toast.error(t('files.openError')))} style={{ color: 'var(--text-primary)', textDecoration: 'underline', background: 'none', border: 'none', cursor: 'pointer', font: 'inherit' }}>{t('files.downloadPdf')}</button>
               </p>
             </object>
           </div>

client/src/i18n/translations/ar.ts

@@ -1222,6 +1222,8 @@ const ar: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'الملفات',
   'files.pageTitle': 'الملفات والمستندات',
   'files.subtitle': '{count} ملف لـ {trip}',
+  'files.download': 'تنزيل',
+  'files.openError': 'تعذر فتح الملف',
   'files.downloadPdf': 'تنزيل PDF',
   'files.count': '{count} ملفات',
   'files.countSingular': 'ملف واحد',

client/src/i18n/translations/br.ts

@@ -1191,6 +1191,8 @@ const br: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Arquivos',
   'files.pageTitle': 'Arquivos e documentos',
   'files.subtitle': '{count} arquivos para {trip}',
+  'files.download': 'Baixar',
+  'files.openError': 'Não foi possível abrir o arquivo',
   'files.downloadPdf': 'Baixar PDF',
   'files.count': '{count} arquivos',
   'files.countSingular': '1 arquivo',

client/src/i18n/translations/cs.ts

@@ -1220,6 +1220,8 @@ const cs: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Soubory',
   'files.pageTitle': 'Soubory a dokumenty',
   'files.subtitle': '{count} souborů pro {trip}',
+  'files.download': 'Stáhnout',
+  'files.openError': 'Soubor nelze otevřít',
   'files.downloadPdf': 'Stáhnout PDF',
   'files.count': '{count} souborů',
   'files.countSingular': '1 soubor',

client/src/i18n/translations/de.ts

@@ -1224,6 +1224,8 @@ const de: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Dateien',
   'files.pageTitle': 'Dateien & Dokumente',
   'files.subtitle': '{count} Dateien für {trip}',
+  'files.download': 'Herunterladen',
+  'files.openError': 'Datei konnte nicht geöffnet werden',
   'files.downloadPdf': 'PDF herunterladen',
   'files.count': '{count} Dateien',
   'files.countSingular': '1 Datei',

client/src/i18n/translations/en.ts

@@ -1281,6 +1281,8 @@ const en: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Files',
   'files.pageTitle': 'Files & Documents',
   'files.subtitle': '{count} files for {trip}',
+  'files.download': 'Download',
+  'files.openError': 'Could not open file',
   'files.downloadPdf': 'Download PDF',
   'files.count': '{count} files',
   'files.countSingular': '1 file',

client/src/i18n/translations/es.ts

@@ -1168,6 +1168,8 @@ const es: Record<string, string> = {
   'files.title': 'Archivos',
   'files.pageTitle': 'Archivos y documentos',
   'files.subtitle': '{count} archivos para {trip}',
+  'files.download': 'Descargar',
+  'files.openError': 'No se pudo abrir el archivo',
   'files.downloadPdf': 'Descargar PDF',
   'files.count': '{count} archivos',
   'files.countSingular': '1 archivo',

client/src/i18n/translations/fr.ts

@@ -1218,6 +1218,8 @@ const fr: Record<string, string> = {
   'files.title': 'Fichiers',
   'files.pageTitle': 'Fichiers et documents',
   'files.subtitle': '{count} fichiers pour {trip}',
+  'files.download': 'Télécharger',
+  'files.openError': "Impossible d'ouvrir le fichier",
   'files.downloadPdf': 'Télécharger le PDF',
   'files.count': '{count} fichiers',
   'files.countSingular': '1 fichier',

client/src/i18n/translations/hu.ts

@@ -1219,6 +1219,8 @@ const hu: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Fájlok',
   'files.pageTitle': 'Fájlok és dokumentumok',
   'files.subtitle': '{count} fájl a következőhöz: {trip}',
+  'files.download': 'Letöltés',
+  'files.openError': 'A fájl megnyitása sikertelen',
   'files.downloadPdf': 'PDF letöltése',
   'files.count': '{count} fájl',
   'files.countSingular': '1 fájl',

client/src/i18n/translations/id.ts

@@ -1279,6 +1279,8 @@ const id: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'File',
   'files.pageTitle': 'File & Dokumen',
   'files.subtitle': '{count} file untuk {trip}',
+  'files.download': 'Unduh',
+  'files.openError': 'Tidak dapat membuka file',
   'files.downloadPdf': 'Unduh PDF',
   'files.count': '{count} file',
   'files.countSingular': '1 berkas',

client/src/i18n/translations/it.ts

@@ -1219,6 +1219,8 @@ const it: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'File',
   'files.pageTitle': 'File e documenti',
   'files.subtitle': '{count} file per {trip}',
+  'files.download': 'Scarica',
+  'files.openError': 'Impossibile aprire il file',
   'files.downloadPdf': 'Scarica PDF',
   'files.count': '{count} file',
   'files.countSingular': '1 documento',

client/src/i18n/translations/nl.ts

@@ -1218,6 +1218,8 @@ const nl: Record<string, string> = {
   'files.title': 'Bestanden',
   'files.pageTitle': 'Bestanden en documenten',
   'files.subtitle': '{count} bestanden voor {trip}',
+  'files.download': 'Downloaden',
+  'files.openError': 'Bestand kon niet worden geopend',
   'files.downloadPdf': 'PDF downloaden',
   'files.count': '{count} bestanden',
   'files.countSingular': '1 bestand',

client/src/i18n/translations/pl.ts

@@ -1170,6 +1170,8 @@ const pl: Record<string, string | { name: string; category: string }[]> = {
   'files.title': 'Pliki',
   'files.pageTitle': 'Pliki i dokumenty',
   'files.subtitle': '{count} plików dla {trip}',
+  'files.download': 'Pobierz',
+  'files.openError': 'Nie można otworzyć pliku',
   'files.downloadPdf': 'Pobierz PDF',
   'files.count': '{count} plików',
   'files.countSingular': '1 plik',

client/src/i18n/translations/ru.ts

@@ -1218,6 +1218,8 @@ const ru: Record<string, string> = {
   'files.title': 'Файлы',
   'files.pageTitle': 'Файлы и документы',
   'files.subtitle': '{count} файлов для {trip}',
+  'files.download': 'Скачать',
+  'files.openError': 'Не удалось открыть файл',
   'files.downloadPdf': 'Скачать PDF',
   'files.count': '{count} файлов',
   'files.countSingular': '1 файл',

client/src/i18n/translations/zh.ts

@@ -1218,6 +1218,8 @@ const zh: Record<string, string> = {
   'files.title': '文件',
   'files.pageTitle': '文件与文档',
   'files.subtitle': '{trip} 的 {count} 个文件',
+  'files.download': '下载',
+  'files.openError': '无法打开文件',
   'files.downloadPdf': '下载 PDF',
   'files.count': '{count} 个文件',
   'files.countSingular': '1 个文件',

client/src/i18n/translations/zhTw.ts

@@ -1278,6 +1278,8 @@ const zhTw: Record<string, string> = {
   'files.title': '檔案',
   'files.pageTitle': '檔案與文件',
   'files.subtitle': '{trip} 的 {count} 個檔案',
+  'files.download': '下載',
+  'files.openError': '無法開啟檔案',
   'files.downloadPdf': '下載 PDF',
   'files.count': '{count} 個檔案',
   'files.countSingular': '1 個檔案',