feat: add admin allow-list controls

[Priveetee]

Summary

• add granular Admin Console allow-list management for global channels, global playlists, and per-user channel/playlist exceptions
• add user search and selected-user allow-list detail without listing every account by default
• send authenticated discovery requests so admins can configure restricted instances while regular restricted users remain filtered
• add family-list blocked states, an optimized blocked GIF, settings section navigation, sidebar separation, and scroll restoration
• keep the existing dev branch ready for main with the allow-list data layer and UI split into focused commits

Production behavior

• admins can configure global and user-scoped allow-list rules from Admin Console > Allow list
• restricted viewers see family-list messaging when a video or listing is blocked
• Settings is split into navigable sections and remembers the last selected section locally
• search/back navigation restores the previous scroll position
• refs Feature Request: Allow List Mode for Channels and Content #112

Deployment requirements

• deploy the matching TypeType-Server allow-list changes before or with this frontend update
• backend must support admin discovery bypass and global allow-list precedence for non-admin accounts
• no new frontend dependencies are added

Runtime verification

• beta backend was redeployed with the allow-list bypass and global restriction fixes
• admin granular allow-list endpoints were smoke-tested for user search, user detail, channel add/remove, and playlist add/remove
• dev branch push checks passed: Coverage, CI, Docker

Tests

• bun run check
• bun run --cwd apps/web tsc -b --force
• bun run knip
• bun run build
• git diff --check

Rollback

• revert the allow-list UI and authenticated discovery commits if Admin Console configuration regresses
• revert the settings section commit if Settings navigation regresses
• revert the scroll restoration commit if back navigation behaves unexpectedly