feat: remove a saved game & redirect on missing/deleted game (#20)

- DELETE /api/games/:id route + Db.delete() (404 when absent)
- PresetPicker: per-saved-game trash button + confirm dialog (Cancel/Delete)
- App: runDeleteGame; useSse onError -> goHome on 'deleted'/'not found'
  (a deleted/missing game now returns the live tab and any deep link home)
- DeleteGameResponse in shared/protocol.ts; api.deleteGame()
- unit test (Db.delete) + 2 e2e tests (home-screen delete; in-flight delete
  returns the active tab home and a fresh deep link lands on home)
- version 0.7.0 -> 0.8.0 + changelog

Fixes #20

server/db.test.ts

@@ -72,4 +72,19 @@ describe('openDb', () => {
     expect(db.load('missing')).toBeNull();
     db.close();
   });
+
+  it('delete removes a game by id and reports absence otherwise', () => {
+    const db = openDb(':memory:');
+    db.save(makeState('a'));
+    db.save(makeState('b'));
+
+    expect(db.delete('nope')).toBe(false); // unknown id
+    expect(db.delete('a')).toBe(true); // removes a
+    expect(db.load('a')).toBeNull();
+    expect(db.load('b')?.id).toBe('b');
+    expect([...db.listIds()].sort()).toEqual(['b']);
+
+    expect(db.delete('a')).toBe(false); // already gone
+    db.close();
+  });
 });