Adds the full keybindings system (26 actions, 5 categories, customizable
and persisted) plus the Ctrl+L "Open Qobuz Link" cross-platform resolver
to the Slint frontend, matching the Tauri implementation 1:1.
- New shared crate qbz-music-link: de-Tauri'd cross-platform link
resolver (Qobuz/Spotify/Apple/Tidal/Deezer/song.link via Odesli) behind
a QobuzSearchBridge trait. src-tauri left untouched.
- src/keybindings.rs: action model, winit shortcut grammar, conflict
detection, ui_prefs persistence, main-window + miniplayer dispatch.
- src/link_resolver.rs: controller + bridge over QbzCore.
- New globals + 3 modals (read-only cheatsheet, customize editor with key
capture, link resolver), hamburger menu entries, and a UiFocusState
text-input guard wired across the app's TextInputs.
cc