perf(playback): keep the history gate off the initial bundle

The `@iptvnator/services` barrel ships in the initial bundle, so adding
PlaybackHistoryGate there (and subscribing to it from the app-wide
ExternalPlaybackService) grew renderer.initialBytes by 1,141 bytes.

- Move the gate to a new lazy-only `playback-data-access` project
  (`@iptvnator/playback/data-access`; scope:shared, domain:playback,
  type:data-access) and register it in the coverage policy.
- The gate subscribes to MPV/VLC session updates itself; it is created by
  the first deferred write, which precedes the launch it waits for.
  ExternalPlaybackService is back to master.
- The Xtream "playlist switched before confirmation" check moves to the
  lazy helper; the initial-path store only takes a `skipListRefresh` flag.

Net effect on this branch: +27 bytes over master (master itself is
108 bytes over the ratchet baseline already).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/coverage/coverage-policy.json

@@ -89,6 +89,13 @@
                 "validationCommand": "pnpm nx test epg-data-access",
                 "e2eTags": ["@epg"]
             },
+            {
+                "name": "playback-data-access",
+                "root": "libs/playback/data-access",
+                "sourceRoot": "libs/playback/data-access/src",
+                "validationCommand": "pnpm nx test playback-data-access",
+                "e2eTags": ["@persistence"]
+            },
             {
                 "name": "m3u-state",
                 "root": "libs/m3u-state",