Unified target-note controls: key filter + fret window across all modes

- New shared PracticeFilter settings (keyTonic/keyMode/fretWindow), persisted
  via AppSettings.practice, defaults off (behavior unchanged).
- music/targetPool.ts: single source for the effective target pool —
  base playable range ∩ fret window ∩ key/mode pitch classes (9 modes incl.
  pentatonic, same scale machinery as Phrase Mode).
- useGameLogic now builds validNotes via computeTargetPool.
- TargetNoteControls component (key on/off + tonic/mode, fret window on/off +
  min/max) rendered in Controls for all game modes; key is independent of the
  displayed key signature.
- Phrase Mode binds its key/fret-window setup to the same shared filter
  (read/write mirror) and drops the duplicate controls in its setup panel.
- Tests: targetPool.test.ts (7 cases); suite 156/156 green, build ok.

src/music/targetPool.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect } from 'vitest';
+import { computeTargetPool } from './targetPool';
+
+const base = {
+    instrumentId: 'guitar',
+    difficulty: 'custom',
+    tuningId: 'standard',
+    customMinFret: 0,
+    customMaxFret: 12,
+    keyEnabled: false,
+    keyTonic: 'C',
+    keyMode: 'major',
+    fretWindowEnabled: false,
+    fretMin: 0,
+    fretMax: 4,
+};
+
+describe('computeTargetPool', () => {
+    it('returns the base playable range when no filters are active', () => {
+        const pool = computeTargetPool(base);
+        expect(pool).toContain(40); // low E
+        expect(pool).toContain(64); // high e (12th fret)
+        expect(pool.length).toBeGreaterThan(30);
+    });
+
+    it('applies the fret window when enabled', () => {
+        const pool = computeTargetPool({ ...base, fretWindowEnabled: true, fretMin: 0, fretMax: 4 });
+        // guitar standard: open strings 40,45,50,55,59,64; window adds up to +4
+        const lo = Math.min(...pool);
+        const hi = Math.max(...pool);
+        expect(lo).toBe(40);
+        expect(hi).toBe(68); // 64 + 4
+        expect(pool).toContain(59); // open g
+        expect(pool).not.toContain(69);
+    });
+
+    it('restricts to pitch classes of the key when key filter is on', () => {
+        const pool = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'major' });
+        const pcs = new Set([0, 2, 4, 5, 7, 9, 11]); // C major
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+        // chromatic notes excluded
+        expect(pool).not.toContain(61); // C# within range
+    });
+
+    it('combines fret window and key filter', () => {
+        const pool = computeTargetPool({ ...base, fretWindowEnabled: true, fretMin: 0, fretMax: 5, keyEnabled: true, keyTonic: 'E', keyMode: 'minor' });
+        const pcs = new Set([4, 6, 7, 9, 11, 0, 2]); // E minor natural: E F# G A B C D
+        expect(pool.length).toBeGreaterThan(0);
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+        // F (pc 5) and F# (pc 6 is in E minor; F natural is not) — F natural excluded
+        expect(pool.some(m => ((m % 12) + 12) % 12 === 5)).toBe(false);
+    });
+
+    it('supports modes beyond the single-note key signatures (dorian)', () => {
+        const pool = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'D', keyMode: 'dorian' });
+        const pcs = new Set([2, 4, 5, 7, 9, 11, 0]); // D dorian: D E F G A B C
+        expect(pool.length).toBeGreaterThan(0);
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+    });
+
+    it('falls back to major for an invalid mode id', () => {
+        const a = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'major' });
+        const b = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'bogus' as string });
+        expect(b).toEqual(a);
+    });
+
+    it('returns an empty pool rather than crashing for a non-fretted window request', () => {
+        const pool = computeTargetPool({ ...base, instrumentId: 'piano', fretWindowEnabled: true });
+        // piano has no fret window: window is ignored, base pool returned
+        expect(pool.length).toBeGreaterThan(0);
+    });
+});