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/downloads/edit.py

@@ -11,7 +11,9 @@ with the worker branching on the asset's `source_kind` to run ffmpeg instead of
                        (the `-ss` seeks first), so a short clip is cheap even from a long source
   * crop (± trim)    → always re-encode (a filter can't be stream-copied), frame-accurate
 
-`edit_spec = {trim?: {start_s, end_s}, crop?: {x, y, w, h}, accurate?: bool}`. `accurate` is the
+`edit_spec = {trim?: {start_s, end_s}, crop?: {x, y, w, h, frame_w?, frame_h?}, accurate?: bool}`. A
+crop with `frame_w`/`frame_h` counts the picture as it is SHOWN, measured on a frame of that size
+(`crop_filter`); one without them is in the file's stored pixels (its older form). `accurate` is the
 per-edit user choice for a trim-only cut (ignored when a crop forces a re-encode anyway). `split`
 is a frontend concept: the
 UI fans a split out into N trim jobs, so there is one output file per job here.
@@ -65,8 +67,9 @@ def _crop_frame(crop: dict) -> dict | None:
     spec from before it was sent, which `crop_filter` cuts in the file's own pixels)."""
     try:
         w, h = int(crop["frame_w"]), int(crop["frame_h"])
-    # silent-ok: no frame is a crop's older form, and it is still the crop that was asked for.
-    except (KeyError, TypeError, ValueError):
+    # silent-ok: no frame is a crop's older form, and it is still the crop that was asked for. An
+    # infinite number (JSON `1e400`) is OverflowError, and it is no more a frame than "x" is.
+    except (KeyError, TypeError, ValueError, OverflowError):
         return None
     return {"frame_w": w, "frame_h": h} if w > 0 and h > 0 else None
 
@@ -85,6 +88,19 @@ def crop_filter(crop: dict) -> str:
     )
 
 
+def crop_stored_size(crop: dict, src_w: int | None, src_h: int | None) -> tuple[int, int] | None:
+    """The stored size `crop_filter` cuts out of a `src_w` x `src_h` file, evened as `EVEN_FRAME`
+    evens it — the clip's size when ffprobe cannot tell. A crop counted in the shown picture is a
+    fraction of the file's frame, not its own pixel count; None when the source size is unknown."""
+    if crop.get("frame_w") and crop.get("frame_h"):
+        if not src_w or not src_h:
+            return None
+        w, h = src_w * crop["w"] // crop["frame_w"], src_h * crop["h"] // crop["frame_h"]
+    else:
+        w, h = crop["w"], crop["h"]
+    return w // 2 * 2, h // 2 * 2
+
+
 def normalize_edit_spec(spec: dict | None) -> dict:
     """Canonicalize a raw edit spec: clamp/round trim, coerce crop to ints, drop empties.
 
@@ -97,7 +113,7 @@ def normalize_edit_spec(spec: dict | None) -> dict:
     if crop:
         try:
             c = {k: int(round(float(crop[k]))) for k in ("x", "y", "w", "h")}
-        except (KeyError, TypeError, ValueError) as exc:
+        except (KeyError, TypeError, ValueError, OverflowError) as exc:
             # The clip still renders — uncropped. The user asked for a crop, got a whole frame,
             # and nothing anywhere called it a failure; this line is the only trace there is.
             log.warning(