feat: 增强 HomeScreen 录音交互与 ChatBloc 状态管理

- 新增录音启动延迟处理，解决权限未就绪时的竞态问题
- 实现历史分页滚动位置保持，提升加载体验
- 添加文本输入框点击键盘显示与焦点管理
- 优化 ChatBloc provider 到 MultiBlocProvider 支持
- 修复 ApiException 429 错误详情解析（支持 JSON 字符串 body）
- 改进 LocalNotificationService 精确闹钟权限请求
- 优化 UiSchemaRenderer GridView children 生成
- 支持导航 action 的 replace 参数
- 移除 Agent router 速率限制逻辑（_allow_run_request, _allow_transcribe_request）
- 补充相关单元测试与集成测试

backend/tests/integration/v1/agent/test_routes.py

@@ -118,13 +118,6 @@ class _FailingStreamAgentService(_FakeAgentService):
 def test_run_requires_auth_and_returns_202_task_id() -> None:
     app.dependency_overrides[get_agent_service] = lambda: _FakeAgentService()
     client = TestClient(app)
-    original_allow_run = agent_router._allow_run_request
-
-    async def _allow_run(*, user_id: str) -> bool:
-        del user_id
-        return True
-
-    agent_router._allow_run_request = _allow_run  # type: ignore[assignment]
 
     try:
         unauthorized = client.post(
@@ -162,7 +155,6 @@ def test_run_requires_auth_and_returns_202_task_id() -> None:
         assert authorized.json()["runId"] == "run-1"
         assert authorized.json()["created"] is False
     finally:
-        agent_router._allow_run_request = original_allow_run  # type: ignore[assignment]
         app.dependency_overrides = {}
 
 
@@ -410,12 +402,6 @@ def test_asr_transcribe_returns_sync_transcript(monkeypatch) -> None:
         id=uuid4(), email="user@example.com"
     )
 
-    async def _allow_transcribe(*, user_id: str) -> bool:
-        del user_id
-        return True
-
-    monkeypatch.setattr(agent_router, "_allow_transcribe_request", _allow_transcribe)
-
     async def mock_transcribe_file(file_path: str, filename: str) -> str:
         assert file_path.endswith(".wav")
         assert filename == "test.wav"
@@ -453,12 +439,6 @@ def test_asr_transcribe_rejects_oversized_audio(monkeypatch) -> None:
 
     monkeypatch.setattr(agent_router, "_MAX_TRANSCRIBE_AUDIO_BYTES", 4)
 
-    async def _allow_transcribe(*, user_id: str) -> bool:
-        del user_id
-        return True
-
-    monkeypatch.setattr(agent_router, "_allow_transcribe_request", _allow_transcribe)
-
     client = TestClient(app)
     oversized = BytesIO(b"12345")
     oversized.name = "test.wav"
@@ -480,12 +460,6 @@ def test_asr_transcribe_rejects_non_wav_audio(monkeypatch) -> None:
         id=uuid4(), email="user@example.com"
     )
 
-    async def _allow_transcribe(*, user_id: str) -> bool:
-        del user_id
-        return True
-
-    monkeypatch.setattr(agent_router, "_allow_transcribe_request", _allow_transcribe)
-
     client = TestClient(app)
     fake_mp3 = BytesIO(b"fake-mp3")
     fake_mp3.name = "test.mp3"
@@ -507,12 +481,6 @@ def test_asr_transcribe_rejects_invalid_wav_payload(monkeypatch) -> None:
         id=uuid4(), email="user@example.com"
     )
 
-    async def _allow_transcribe(*, user_id: str) -> bool:
-        del user_id
-        return True
-
-    monkeypatch.setattr(agent_router, "_allow_transcribe_request", _allow_transcribe)
-
     client = TestClient(app)
     fake_payload = BytesIO(b"not-a-wav")
     fake_payload.name = "test.wav"
@@ -527,33 +495,3 @@ def test_asr_transcribe_rejects_invalid_wav_payload(monkeypatch) -> None:
         assert response.json()["detail"] == "Unsupported audio format"
     finally:
         app.dependency_overrides = {}
-
-
-def test_asr_transcribe_rejects_when_rate_limited_for_current_user(monkeypatch) -> None:
-    known_user = CurrentUser(id=uuid4(), email="user@example.com")
-    app.dependency_overrides[get_current_user] = lambda: known_user
-
-    captured_user_ids: list[str] = []
-
-    async def _deny_transcribe(*, user_id: str) -> bool:
-        captured_user_ids.append(user_id)
-        return False
-
-    monkeypatch.setattr(agent_router, "_allow_transcribe_request", _deny_transcribe)
-
-    client = TestClient(app)
-    wav_content = b"RIFF\x24\x80\x00\x00WAVEfmt "
-    wav_file = BytesIO(wav_content)
-    wav_file.name = "test.wav"
-
-    try:
-        response = client.post(
-            "/api/v1/agent/transcribe",
-            files={"audio": ("test.wav", wav_file, "audio/wav")},
-        )
-
-        assert response.status_code == 429
-        assert response.json()["detail"] == "Too many transcribe requests"
-        assert captured_user_ids == [str(known_user.id)]
-    finally:
-        app.dependency_overrides = {}