fix(trash): close active-query invariant leaks (review T5 important #1+#2)

T5 reviewer identified 2 reads outside NoteRepository that were missing the
'WHERE deleted_at IS NULL' filter, breaking the silent invariant beyond the
3 originally-listed methods.

- ContinuityService.get() now excludes trashed notes from streak / weekCount
  / lastNoteAt / recovery-toast math. A trashed note no longer counts toward
  weekly streak (regression: streak felt fake after trash).
- NoteRepository.getPendingCount() now excludes trashed-but-still-pending
  notes. trash() removes the pending_jobs row but leaves notes.ai_status='pending';
  the count would have drifted upward as users trashed pending notes.
- MediaGc.run() gets an inline comment documenting why it intentionally does
  NOT filter — trashed notes still own their media until permanentDelete /
  emptyTrash. Removing here would defeat restore.

Also: migrations.due_date.test.ts had 2 brittle assertions
(latestVersion()===2, user_version===2) that broke with v3. Migration-system
version assertions belong in migrations.test.ts (already covered there);
m002-specific test keeps the due_date column assertion which is version-stable.

Tests: 245 → 265 (+20). typecheck 0 errors.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/NoteRepository.test.ts

@@ -403,4 +403,14 @@ describe('Active queries exclude deleted notes', () => {
     expect(note).not.toBeNull();
     expect(note!.deletedAt).toBe('2026-05-01T00:00:00.000Z');
   });
+
+  it('getPendingCount() excludes trashed pending notes (drift guard)', () => {
+    const a = repo.create({ rawText: 'a' }).id; // ai_status=pending
+    repo.create({ rawText: 'b' }); // ai_status=pending
+    expect(repo.getPendingCount()).toBe(2);
+    // trash() 가 pending_jobs row 는 정리하지만 notes.ai_status 는 'pending' 그대로.
+    // getPendingCount 가 deleted_at IS NOT NULL 노트 포함하면 영구 over-count.
+    repo.trash(a, '2026-05-01T00:00:00.000Z');
+    expect(repo.getPendingCount()).toBe(1);
+  });
 });