feat(channels): add manage channels TV surface

[MrFr3di]

Scope

Stacked on #245. Implements CC-3: a dedicated TV-first Manage Channels surface backed by the profile-scoped canonical management projection and ChannelPreferences mutations.

Planned behavior:

• entry from the Channels header, not Settings;
• explicit All / Visible / Hidden filters;
• hidden channels remain recoverable;
• row OK opens management actions rather than playback;
• hide/unhide, rename, custom channel number, reset customization;
• preserve Favorite on reset;
• deterministic focus recovery when a focused row disappears;
• no long-OK quick actions in this slice (CC-4);
• no EPG enrichment or provider/source-specific editing.

The first commit is intentionally RED-first and defines the ViewModel/query/mutation contract. This PR remains draft until the stacked base and exact-head checks are green.

[MrFr3di]

Closing as superseded by #254, which is the canonical CC-3 Manage Channels TV surface. This branch covers the same product slice on the same #245 management projection. Keeping both open would create duplicate restack/verification work and ambiguous ownership.