refactor(player): E.7 — extract two small file-private helpers (#570)

`emitNormalizationDebug` (debug-mode trace forwarder, 15+ internal call
sites) and `isInOrbitSession` (Orbit-active guard used by next() and the
async fallback paths to suppress local queue extensions, 5 call sites)
move into dedicated modules under src/store/. Both were file-private —
no caller-side changes outside playerStore's own imports.

playerStore 3434 → 3415 LOC.

src/store/normalizationDebug.test.ts

@@ -0,0 +1,51 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const { authState, invokeMock } = vi.hoisted(() => ({
+  authState: { loggingMode: 'off' as 'off' | 'debug' | string },
+  invokeMock: vi.fn(async (_cmd: string, _args?: Record<string, unknown>) => undefined),
+}));
+
+vi.mock('@tauri-apps/api/core', () => ({ invoke: invokeMock }));
+vi.mock('./authStore', () => ({ useAuthStore: { getState: () => authState } }));
+
+import { emitNormalizationDebug } from './normalizationDebug';
+
+beforeEach(() => {
+  authState.loggingMode = 'off';
+  invokeMock.mockClear();
+  invokeMock.mockResolvedValue(undefined);
+});
+
+describe('emitNormalizationDebug', () => {
+  it('is a no-op when logging mode is not debug', () => {
+    emitNormalizationDebug('refresh:start', { trackId: 't1' });
+    expect(invokeMock).not.toHaveBeenCalled();
+  });
+
+  it('forwards a JSON payload to frontend_debug_log in debug mode', () => {
+    authState.loggingMode = 'debug';
+    emitNormalizationDebug('refresh:start', { trackId: 't1' });
+    expect(invokeMock).toHaveBeenCalledTimes(1);
+    const [cmd, args] = invokeMock.mock.calls[0];
+    expect(cmd).toBe('frontend_debug_log');
+    expect(args).toMatchObject({
+      scope: 'normalization',
+      message: JSON.stringify({ step: 'refresh:start', details: { trackId: 't1' } }),
+    });
+  });
+
+  it('serializes calls without details too', () => {
+    authState.loggingMode = 'debug';
+    emitNormalizationDebug('plain-step');
+    const args = invokeMock.mock.calls[0][1] as { message: string };
+    expect(JSON.parse(args.message)).toEqual({ step: 'plain-step' });
+  });
+
+  it('swallows invoke rejections (best-effort instrumentation)', async () => {
+    authState.loggingMode = 'debug';
+    invokeMock.mockRejectedValueOnce(new Error('rust busy'));
+    expect(() => emitNormalizationDebug('refresh:start')).not.toThrow();
+    // Give the rejected promise a tick to settle without throwing.
+    await Promise.resolve();
+  });
+});