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.

frontend/src/watch/WatchPage.tsx

@@ -64,7 +64,7 @@ type Meta = FileMeta | FolderMeta;
 // What the link answers before it is opened: a password link says only which kind it is.
 type Answer =
   | (Meta & { needs_password?: false })
-  | { needs_password: true; kind?: "file" | "folder" };
+  | { needs_password: true; kind?: "file" | "folder"; video?: boolean };
 
 // Compact display of a URL: drop the protocol + trailing slash so it fits on one line.
 function displayUrl(url: string): string {
@@ -97,8 +97,9 @@ export default function WatchPage() {
     "loading" | "ready" | "password" | "gone" | "preparing" | "error"
   >(token ? "loading" : "gone");
   const [meta, setMeta] = useState<Meta | null>(null);
-  // A password link's kind, for its title, until it is unlocked.
-  const [locked, setLocked] = useState<"file" | "folder">("file");
+  // What a password link opens, for its prompt's words, until it is unlocked. A server from before
+  // it said `video` only had video links' words, so a file without it reads as one.
+  const [locked, setLocked] = useState<"video" | "file" | "folder">("video");
   const [password, setPassword] = useState("");
   const [error, setError] = useState<string | null>(null);
   const errorId = useId();
@@ -124,7 +125,7 @@ export default function WatchPage() {
       .then((m) => {
         if (typeof m === "string") setStatus(m);
         else if (m.needs_password) {
-          setLocked(m.kind ?? "file");
+          setLocked(m.kind === "folder" ? "folder" : m.video === false ? "file" : "video");
           setStatus("password");
         } else {
           setMeta(m);
@@ -246,7 +247,11 @@ export default function WatchPage() {
             <div className={`${SURFACE.panel} w-full max-w-sm p-6`}>
               <div className="flex items-center gap-2 font-medium mb-4">
                 <Lock className="w-4 h-4 text-accent" />{" "}
-                {locked === "folder" ? T.passwordTitleFolder : T.passwordTitle}
+                {locked === "folder"
+                  ? T.passwordTitleFolder
+                  : locked === "file"
+                    ? T.passwordTitleFile
+                    : T.passwordTitle}
               </div>
               <Input
                 className="w-full"
@@ -272,7 +277,7 @@ export default function WatchPage() {
                 disabled={!password || unlocking}
                 className="mt-4"
               >
-                {T.watch}
+                {locked === "video" ? T.watch : T.open}
               </Button>
             </div>
           </div>