feat: XMLTV EPG fallback, Warm Cinema theme, background release

Align the Android app with xtremflow on three fronts.

EPG: add XmltvService, a streaming XMLTV parser (gunzip-aware, indexed to a
-3h/+18h window, JSON disk cache with a 6h TTL). XtreamServiceMobile now falls
back through the provider's xmltv.php, a user-supplied URL, then a community
guide whenever get_short_epg returns nothing. Channels are matched on
epg_channel_id first, then on a normalized name (accents, HD/FHD/4K suffixes,
"FR:" and "|FR|" prefixes). A streamId -> Channel index populated by
getLiveChannels supplies those keys, so no getShortEPG call site changed.
EPG requests are also funnelled through a 3-slot semaphore, as in xtremflow:
a 30-tile grid used to fire 30 parallel player_api.php calls, which rate-limited
panels answered with errors, emptying the guide for the whole screen.

Theme: port the Warm Cinema charter (ember/charcoal/cream, Fraunces + Karla)
into app_colors, app_theme and app_decorations. The 21 Apple TV colour names
already in use are kept as compatibility aliases. mobile_theme now derives from
AppTheme instead of duplicating its 390 lines.

Playback lifecycle: stop reacting to AppLifecycleState.inactive, which fires on
transient Android interruptions such as pulling down the notification shade and
was killing playback. Both engines now release on paused/hidden/detached via
_releasePlayback(): stream stopped, decoder released, timers cancelled, wakelock
dropped. An _isReleased latch keeps the watchdog and reconnect paths from
restarting a stream from the background.

Long-run stability: cancel the six player stream subscriptions on dispose, cap
demuxer-max-back-bytes at 8MB (mpv defaults to 50MiB, which combined with the
150MB readahead pushed the native heap toward an Android memory kill after a few
hours), rebuild on position only while the controls are visible, and dispose the
Lite player's focus nodes.

Startup: prewarmHost() pre-resolves DNS and opens then closes a bare TCP/TLS
socket before playback. No HTTP request is issued, so no provider connection
slot is consumed. Capped at 1.5s.

Verified: flutter analyze clean on all touched files; 19/19 tests, including a
run over a real 46MB/69802-programme dump (517 channels indexed in 1.1s, 5/5
name probes matched); flutter build apk --release succeeds.

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

pubspec.yaml

@@ -1,7 +1,7 @@
 name: xtremobile
 description: High-performance IPTV Android Application with Xtream Codes API
 publish_to: 'none'
-version: 1.5.1+11
+version: 1.6.0+12
 
 environment:
   sdk: '>=3.0.0 <4.0.0'
@@ -23,6 +23,9 @@ dependencies:
   dio_cache_interceptor: ^3.5.1
   dio_cache_interceptor_hive_store: ^3.2.2
   http: ^1.2.2
+
+  # EPG (XMLTV fallback parsing)
+  xml: ^6.5.0
   
   # Routing
   go_router: ^13.2.5