fix(synology): correct multi-album passphrase assignment and stale trek_photos

- ProviderPicker now tracks per-asset album passphrase in a Map; on confirm,
  assets are grouped by passphrase and submitted as separate batches so each
  asset receives its own album's passphrase instead of the last-selected one
- getOrCreateTrekPhoto unconditionally overwrites the stored passphrase when
  a fresh one is supplied, allowing re-adds to heal a stuck bad passphrase
- deleteTrekPhotoIfOrphan purges the trek_photos row for provider assets when
  no trip_photos or journey_photos reference it anymore; wired into
  removeTripPhoto, removeAlbumLink, and deletePhoto so remove + re-add is a
  clean slate
- Three new integration tests: SYNO-090 (passphrase overwrite), SYNO-091
  (orphan cleanup), SYNO-092 (remove + re-add restores correct passphrase)

server/src/services/memories/photoResolverService.ts

@@ -22,7 +22,7 @@ export function getOrCreateTrekPhoto(
   ).get(provider, assetId, ownerId) as { id: number } | undefined;
   if (existing) {
     if (passphrase) {
-      db.prepare('UPDATE trek_photos SET passphrase = ? WHERE id = ? AND passphrase IS NULL')
+      db.prepare('UPDATE trek_photos SET passphrase = ? WHERE id = ?')
         .run(encrypt_api_key(passphrase), existing.id);
     }
     return existing.id;
@@ -145,6 +145,19 @@ export function setTrekPhotoProvider(
   ).run(provider, assetId, ownerId, trekPhotoId);
 }
 
+// ── Orphan cleanup ───────────────────────────────────────────────────────
+
+export function deleteTrekPhotoIfOrphan(photoId: number): void {
+  const stillUsed = db.prepare(`
+    SELECT 1 FROM trip_photos WHERE photo_id = ?
+    UNION ALL
+    SELECT 1 FROM journey_photos WHERE photo_id = ?
+    LIMIT 1
+  `).get(photoId, photoId);
+  if (stillUsed) return;
+  db.prepare("DELETE FROM trek_photos WHERE id = ? AND provider != 'local'").run(photoId);
+}
+
 // ── Delete local file for a trek_photo ──────────────────────────────────
 
 export function getTrekPhotoFilePath(photoId: number): string | null {