feat(playback): embedded mpv pre-0.22 hardening, Linux parity, and localization (#1122)

* fix(playback): harden embedded mpv session handling and support detection

- guard the session controller against late startup rejections clobbering
  a newer session during fast channel zapping
- exclude the refresh timestamp from the session-update dedup key so idle
  sessions stop re-emitting IPC updates every 500 ms
- macOS: reconcile async loadfile replies by request id so a rejected
  seek/aid/speed on a live stream no longer flips the session to error
- append --ozone-platform=x11 on Linux in main.ts so direct binary and
  AppImage launches match the packaged .desktop launcher behavior
- return a sandbox-specific unsupported reason in Flatpak/Snap instead of
  asking the user to install mpv inside the sandbox
- update the stale "macOS only" embedded MPV claim in CLAUDE.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(playback): populate Linux audio tracks and fix ARM Linux packaging

- Linux poller now reads track-list/count each tick and walks the scalar
  track-list/N/* sub-properties when the count changes, so the audio-track
  menu is no longer empty; selection reconciles from the aid property
- afterPack replaces the x64 embedded_mpv.node with an
  embedded-mpv-unavailable.txt marker in arm64/armv7l Linux packages, and
  package-layout verification rejects foreign-architecture addons while
  requiring the marker
- extend native source invariants for the non-fatal async-reply rule
  (macOS) and the Linux track-list polling contract
- document the Linux track-list mechanics and ARM packaging behavior in
  docs/architecture/embedded-mpv-native.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* feat(playback): embedded mpv player UX polish and full localization

- click on the video toggles pause (same action as Space) with a 250 ms
  grace period so double-click fullscreen cancels the pending pause; no
  DOM overlay is drawn — the dock transport icon is the feedback
- timeline scrubbing previews the drag position locally and commits a
  single seek on release instead of one IPC seek per drag pixel
- translate all player UI strings (controls, tooltips, aria-labels,
  status and recording messages) via new EMBEDDED_MPV.PLAYER.* keys,
  synced across en + 17 locales through the i18n-fill workflow
- replace the legacy @Output() EventEmitter with the signal output() API

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(playback): react to language changes and respect ozone platform hint

Address review feedback on #1122:
- add a translationsTick signal (onLangChange/onTranslationChange/
  onDefaultLangChange) read by every computed() and template helper that
  calls translate.instant(), so labels re-evaluate on a runtime language
  switch and when the translation file finishes loading after mount
- suppress the Linux --ozone-platform=x11 fallback when the user set
  ELECTRON_OZONE_PLATFORM_HINT, matching the existing respect for an
  explicit --ozone-platform switch

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

apps/web/src/app/embedded-mpv-player-recording-message.spec.ts

@@ -1,6 +1,7 @@
 import { Component, signal } from '@angular/core';
 import { ComponentFixture, TestBed } from '@angular/core/testing';
 import { By } from '@angular/platform-browser';
+import { TranslateModule, TranslateService } from '@ngx-translate/core';
 import { ResolvedPortalPlayback } from '@iptvnator/shared/interfaces';
 import {
     EmbeddedMpvOverlayVisibilityService,
@@ -31,7 +32,7 @@ describe('EmbeddedMpvPlayerComponent recording status message', () => {
         } as unknown as typeof window.electron;
 
         await TestBed.configureTestingModule({
-            imports: [EmbeddedMpvPlayerHostComponent],
+            imports: [EmbeddedMpvPlayerHostComponent, TranslateModule.forRoot()],
             providers: [
                 {
                     provide: EmbeddedMpvOverlayVisibilityService,
@@ -44,6 +45,17 @@ describe('EmbeddedMpvPlayerComponent recording status message', () => {
             })
             .compileComponents();
 
+        const translate = TestBed.inject(TranslateService);
+        translate.setTranslation('en', {
+            EMBEDDED_MPV: {
+                PLAYER: {
+                    SAVED_TO: 'Saved to {{path}}',
+                    RECORDING_SAVED: 'Recording saved',
+                },
+            },
+        });
+        translate.use('en');
+
         fixture = TestBed.createComponent(EmbeddedMpvPlayerHostComponent);
         fixture.detectChanges();