fix: share, upload, crop, auto-skip, tag chips and See all hold what they claim

- Share: a link that expired is never copied (the dialog and one-click Share pick a live one,
  else make one), says it expired, and the copy-on-open claim clears on the next copy.
- A password-protected file link asks to open a file, not to watch a video.
- Upload: Cancel, the close button or the backdrop while naming a folder makes no folder; a failed
  refetch keeps the target; a folder being made says so.
- Crop: an infinite number is dropped, not a 500; an unprobed clip's size follows a shown-size crop;
  the edit_spec docs name frame_w/frame_h; the join and rotated paths are tested.
- Auto-skip: the wait gives way on a marker too short for it, so the skip still fires.
- Tag chips count the followed channels (subscribed_count) and a toggled chip keeps the focus.
- Continue watching's See all sorts by last watched when in progress was already on.

backend/app/routes/public.py

@@ -176,8 +176,15 @@ def watch_meta(token: str, db: Session = Depends(get_db)) -> dict:
     returns only `needs_password` until the viewer unlocks it (no title/thumbnail leak)."""
     link = _link_or_404(db, token)
     if link.password_hash:
-        # Which kind it opens, for the password prompt's title — never what is in it.
-        return {"needs_password": True, "kind": "folder" if link.folder_id is not None else "file"}
+        # Which kind it opens, for the password prompt's words — never what is in it. `video` tells
+        # a video (watched) from any other file (opened); the address is only a hint, every
+        # prefix opens every link.
+        opens = linksmod.opens(db, link)
+        return {
+            "needs_password": True,
+            "kind": "folder" if opens == "folder" else "file",
+            "video": opens == "video",
+        }
     meta = _opened(db, link, token)
     db.commit()
     return meta

backend/app/routes/tags.py

@@ -48,8 +48,9 @@ def list_tags(user: User = Depends(current_user), db: Session = Depends(get_db))
             "category": tag.category,
             "system": tag.user_id is None,
             "channel_count": count,
+            "subscribed_count": subscribed,
         }
-        for tag, count in queries.tags_with_counts(db, user)
+        for tag, count, subscribed in queries.tags_with_counts(db, user)
     ]