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/tests/test_share_paths.py

@@ -135,3 +135,14 @@ def test_a_card_of_a_video_stays_a_video(shared, db):
     assert f"/watch/{made['token']}" in tags and "video.other" in tags
     locked = shared("other.mp4", _VIDEO, password="pw")
     assert "Password-protected video" in og._watch_tags(locked["token"], db)
+
+
+@pytest.mark.parametrize(
+    ("name", "data", "video"),
+    [("clip.mp4", _VIDEO, True), ("song.m4a", _AUDIO, False), ("backup.tar.gz", None, False)],
+)
+def test_a_password_link_says_whether_it_opens_a_video(shared, client, name, data, video):
+    """The lock screen asks to watch a video and to open anything else, whichever path it is on."""
+    token = shared(name, data, password="pw")["token"]
+    meta = client.get(f"/api/public/watch/{token}").json()
+    assert meta == {"needs_password": True, "kind": "file", "video": video}