Fix Disney+ force sync, seek, and HCM regressions for v2.5.3

The v2.5.2 Disney+ page-API integration leaked blob-relative <video>
time into force sync, seeks, and heartbeats when the page-API bridge
had no fresh data, so force sync on Disney+ appeared broken.

- getSyncCurrentTime/getSyncDuration now refuse native values on Disney+
  (return null/0) so stale bridge data degrades to a clean no-op instead
  of broadcasting garbage to peers. The get_current_time handler and
  episode/lobby/hcmIsLive paths are routed through the same accessor.
- Validate FORCE_SYNC_PREPARE/SEEK payloads as finite before relaying;
  the internal coercion no longer treats '' as 0.
- Stop double-routing FORCE_SYNC_PREPARE from the popup path (the
  generic popup route now covers only play/pause/seek).
- popup force-sync: exclude null/empty peer times from the jump-to-others
  median (Number(null)===0 was dragging the target to 0), guard against
  NaN end-to-end, clear the dangling reset timer on failure, and retry
  without re-injecting when the content script responds but the Disney+
  bridge has not yet delivered a finite time.
- hcmIsLive skips the native-duration live signal on Disney+ only,
  preserving YouTube/Twitch Infinity-duration live detection.

Disney-specific logic remains strictly gated to disneyplus.com; no
Netflix/YouTube/Twitch/generic path is affected.

scripts/test-content-video-finder.cjs

@@ -122,6 +122,10 @@ const disneyVideo = makeVideo('disney-offset', 1920, 1080, {
 assert.equal(disneyFns.getSyncCurrentTime(disneyVideo), 9);
 assert.equal(disneyFns.getSyncDuration(disneyVideo), 10800);
 assert.equal(disneyFns.toNativeSeekTime(disneyVideo, 39), 39);
+assert.equal(disneyFns.getSyncCurrentTime(makeVideo('disney-native-broken', 1920, 1080, {
+  currentTime: Number.NaN,
+  duration: 0
+})), 9);
 
 const disneyNoPageApiFns = loadTimelineFns('www.disneyplus.com');
 const disneyOffsetVideo = makeVideo('disney-offset', 1920, 1080, {
@@ -129,7 +133,7 @@ const disneyOffsetVideo = makeVideo('disney-offset', 1920, 1080, {
   duration: 0,
   seekable: makeSeekable([[20, 10820]])
 });
-assert.equal(disneyNoPageApiFns.getSyncCurrentTime(disneyOffsetVideo), 29);
+assert.equal(disneyNoPageApiFns.getSyncCurrentTime(disneyOffsetVideo), null);
 assert.equal(disneyNoPageApiFns.getSyncDuration(disneyOffsetVideo), 0);
 assert.equal(disneyNoPageApiFns.toNativeSeekTime(disneyOffsetVideo, 39), 39);