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/lib/plexPlayerHooks.skip.dom.test.ts

@@ -0,0 +1,16 @@
+// @vitest-environment jsdom
+//
+// An auto-skip's countdown starts below zero: the wait before it, while the Skip button already
+// shows. The bar it draws must read empty through the wait, not a negative width.
+import { describe, expect, it } from "vitest";
+
+import { skipCountdown } from "./plexPlayerHooks";
+
+describe("skipCountdown", () => {
+  it("stays empty through the wait, runs over the delay, and stops at full", () => {
+    expect(skipCountdown(-3, 5)).toBe(0);
+    expect(skipCountdown(-0.1, 5)).toBe(0);
+    expect(skipCountdown(2.5, 5)).toBe(0.5);
+    expect(skipCountdown(7, 5)).toBe(1);
+  });
+});