feat: add single-select library picker mode

[everpcpc]

Problem

Library filtering only supported the existing multi-select flow, which made quick single-library switching feel heavier than necessary. On tvOS, the picker was also not reachable from the dashboard flow, so library filtering depended on less-obvious fallback screens.

Approach

Add a toggleable single-select mode to the shared library picker and move selection to whole-row taps with explicit selection indicators. In single-select mode, picking a library immediately applies the filter and dismisses the sheet. Add a dedicated tvOS dashboard entry point so the same picker remains reachable on Apple TV.

Scope

• Add single-select and multi-select mode switching in the library picker sheet
• Update library rows to use row selection indicators instead of per-row toggles
• Add a tvOS dashboard button to open the library picker
• Sync localized labels and bump the build number to 374

Validation

• make format
• make build
• make localize
• ./misc/translate.py list