- Strings filter: per-string toggle buttons (replaces fret-window-only
semantics as a third 'limits notes' control); combines with fret window
and key filter in targetPool (fretted instruments).
- Key sync checkbox: display key signature can follow the target key
(major/minor mapping), default off — both remain independently settable.
- LiveNoteStaff: optional fixed clef — guitar/bass now keep their usual
clef instead of flipping at middle C; octave markers handle range.
- Unified metronome widget (MetronomeWidget) with animated linear pendulum
synced to the audible click; shown in ALL modes next to the tuner.
Phrase BPM now reads from settings.rhythm.bpm (single source); the
phrase-local BPM control was removed from the setup panel.
- Tests: 160/160; tsc + eslint clean; build ok.
