docs: sync the DASH/Shaka contract across agent docs

Mirrors the DASH/Shaka source-engine contract into AGENTS.md and adds
Shaka to the shared web-video bridge descriptions in CLAUDE.md and the
player-controls contract; documents the lazy raw-KODIPROP DRM fallback
for pre-upgrade playlists in the M3U architecture doc.

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

docs/architecture/m3u-playlist-module.md

@@ -689,8 +689,12 @@ player in settings.
 3. The typed result lands on `Channel.drm` (`ChannelDrm` in
    `@iptvnator/shared/interfaces`), travels through
    `ResolvedPortalPlayback.drm` into `WebPlayerViewComponent`'s synthetic
-   channel, and reaches the engine. Persistence is free (playlist JSON blob /
-   IndexedDB object).
+   channel, and reaches the engine. Persistence is free for newly imported or
+   refreshed playlists (playlist JSON blob / IndexedDB object). Playlists
+   imported **before** the DRM feature carry no `drm` field yet, but the raw
+   `#KODIPROP` block survived in the stored items — the M3U player page falls
+   back to `extractDrmFromRaw(channel.raw)` at playback time, so encrypted
+   channels of pre-upgrade playlists work without a re-import.
 
 **Engine selection and routing:**
 

docs/architecture/player-controls-contract.md

@@ -37,7 +37,7 @@ those control systems is active at a time.
 
 When `WEB_PLAYER_SHARED_CONTROLS` is enabled, the built-in HTML5 player mounts
 the same presentation component over its real player shell and disables the
-native video controls. Its neutral source bridge supplies HLS/native tracks,
+native video controls. Its neutral source bridge supplies HLS/Shaka/native tracks,
 corrected MPEG-TS VOD duration, and authoritative live/VOD metadata to the
 generic web adapter. When the host token resolves to false, the native controls
 and legacy series navigation remain unchanged and the adapter is not attached.
@@ -50,7 +50,7 @@ keeps its existing skin and legacy series navigation.
 
 ArtPlayer is the fourth consumer. Its source session owns HLS, MPEG-TS, native
 source selection, and delayed `customType` callbacks, while the neutral
-web-video source bridge exposes HLS/native tracks, caption preference, and
+web-video source bridge exposes HLS/Shaka/native tracks, caption preference, and
 MPEG-TS VOD duration to the adapter. Its video session owns native media and
 ArtPlayer event listeners. Shared mode uses authoritative live/VOD metadata,
 reapplies the app volume directly to the media element after ArtPlayer restores
@@ -643,7 +643,7 @@ libs/ui/playback/src/lib/art-player/
 ```
 
 `ArtPlayerComponent` provides a component-scoped `WebVideoControlsAdapter`.
-`ArtPlayerSourceSession` owns HLS/MPEG-TS/native engines, the neutral source
+`ArtPlayerSourceSession` owns HLS/DASH(Shaka)/MPEG-TS/native engines, the neutral source
 bridge, exact engine/listener cleanup, and a destroyed-session guard for
 ArtPlayer's delayed `customType` dispatch. `ArtPlayerVideoSession` owns native
 media errors, readiness, volume persistence, ended/time updates, and exact