feat(channels): add channel management TV surface

[MrFr3di]

Scope

CC-3 stacked on #245. Adds the dedicated TV Manage Channels surface on top of the canonical/profile-scoped Channel Control mutation and management projection layers.

Planned in this slice:

• non-top-level ManageChannels destination under Channels;
• explicit ALL / VISIBLE / HIDDEN management filters;
• TV/D-pad management list backed by ChannelBrowseRepository.managementPages;
• rename, custom channel number, hide/unhide, and reset customization actions through ChannelPreferencesRepository;
• TV-native/foundation text input pattern already used by source onboarding;
• deterministic focus recovery when a mutation removes the current row from the selected visibility projection;
• no Room schema change;
• no arbitrary manual reorder;
• no normal-channel long-press quick actions yet (CC-4).

The first commit is RED-first and defines the management ViewModel contract. The PR remains draft until exact-head checks are green.

Temporarily targeted at main only to trigger the repository's PR CI; after validation it will be restored to the stacked base feature/channel-control-management-projection.

[MrFr3di]

Closing as superseded by the later canonical CC-3 implementation PR #254. Both target the same Manage Channels surface over #245; keeping parallel UI variants open makes the Channel Control restack ambiguous. Any accepted behavior from this branch must be validated against #254/current main rather than merged separately.