feat(studio): filter photos by entry, upload from Studio, and switch stops off

The content browser gets a filter over the journey's pictures: all of them,
the ones no entry holds, or one entry at a time, with the day and the place
under each name. An entry card in the Entries tab reaches its own pictures
the same way. Pictures can now come in without leaving Studio, into the
entry the filter names or into the gallery, from the panel or dropped
straight onto the page, and a photo element can fill its page or the whole
spread in one press.

Stops can be taken out of the arithmetic. A journal entry carries a
stats_excluded flag; an entry that has it is off the route, out of the
distance, out of the countries and not a step, while staying in the
journal. Studio lists every stop in the travel panel with a switch, the
entry editor carries the same switch on desktop and phone, and the entry
card says when a day is off the route.

client/src/components/Studio/StudioShell.tsx

@@ -89,6 +89,9 @@ export default function StudioShell() {
             path={s.path}
             t={s.t}
             locale={s.locale}
+            canEdit={s.canEdit}
+            onUpload={s.uploadPhotos}
+            onToggleStop={s.setStopExcluded}
           />
           <Workbench s={s} bookView={bookView} />
           <StudioInspector
@@ -431,7 +434,20 @@ function Workbench({ s, bookView }: { s: Studio; bookView: boolean }) {
           dropLabel={s.t('journey.studio.dropPhotoHere')}
           cursors={s.cursors}
           onCursor={(x, y) => s.moveCursor(s.activeSpread, x, y)}
+          onDropFiles={s.canEdit ? s.dropFiles : undefined}
+          fileDropLabel={s.t('journey.studio.dropFilesHere')}
         />
+        {/*
+          Pictures dropped on the sheet are on their way. The page keeps
+          rendering underneath; the veil only says that something is happening
+          where the pointer let go, so the second or two before the frame
+          appears does not read as the drop having been ignored.
+        */}
+        {s.canvasUpload && (
+          <div className="st-upload-veil" role="status" aria-live="polite">
+            {s.t('journey.studio.uploading', { done: s.canvasUpload.done, total: s.canvasUpload.total })}
+          </div>
+        )}
       </div>
 
       <div className="st-zoom">