fix: 修复 Liblib provider 认证和多个图片生成关键缺陷

- 重写 LiblibImageProvider：Bearer token 改为 HMAC-SHA1 签名认证，
  适配 Liblib 真实 API（Star-3 Alpha 文生图端点）
- 修复 chapter.images JSON 列原地修改不持久化（深拷贝+整列重赋值）
- 修复 generate_chapter_images 在事务提交前派发（改为 commit 后统一 delay）
- 修复 initialize_chapter_images 覆盖已完成图片（新增 merge 去重逻辑）
- 修复 Android failed 图片渲染为错误卡片（改为隐藏，保持正文连续）
- 模型模板 UUID 改为环境变量配置（LIBLIB_TEMPLATE_UUID）
- 更新 .env 凭证格式为 ACCESS_KEY/SECRET_KEY
- 补充 test_memoir_image_bootstrap 缺失的 unittest.mock 导入

Made-with: Cursor

api/tests/test_process_memoir_segments_image_enqueue.py

@@ -0,0 +1,74 @@
+import unittest
+from types import SimpleNamespace
+from unittest.mock import Mock, patch
+
+from api.tasks.memoir_tasks import MemoirImageSettings, process_memoir_segments
+
+
+class ProcessMemoirSegmentsImageEnqueueTest(unittest.TestCase):
+    @patch("api.tasks.memoir_tasks._update_task_status_sync")
+    @patch("api.tasks.memoir_tasks._release_chapter_lock")
+    @patch("api.tasks.memoir_tasks._acquire_chapter_lock", return_value=True)
+    @patch("api.tasks.memoir_tasks._classify_chapter_category", return_value="childhood")
+    @patch("api.tasks.memoir_tasks._get_or_create_state_sync")
+    @patch("api.tasks.memoir_tasks.llm_service.get_llm", return_value=None)
+    @patch("api.tasks.memoir_tasks.generate_chapter_images.delay")
+    @patch("api.tasks.memoir_tasks.SessionLocal")
+    @patch("api.tasks.memoir_tasks.MemoirImageSettings.from_env")
+    def test_process_memoir_segments_enqueues_image_jobs_after_commit(
+        self,
+        settings_from_env,
+        session_local_cls,
+        delay_mock,
+        _get_llm,
+        get_state_mock,
+        _classify_mock,
+        _acquire_lock_mock,
+        _release_lock_mock,
+        _update_status_mock,
+    ):
+        settings_from_env.return_value = MemoirImageSettings(
+            enabled=True,
+            max_per_chapter=2,
+            provider="liblib",
+            default_style="watercolor",
+            default_size="1024x1024",
+            poll_interval_seconds=3,
+            max_attempts=20,
+        )
+        get_state_mock.return_value = SimpleNamespace(current_stage="childhood", slots={})
+
+        segment = SimpleNamespace(
+            id="segment-1",
+            transcript_text="那条路我一直记得。\n\n{{{{IMAGE:南方小镇的青石板路}}}}",
+            processed=False,
+        )
+
+        segments_result = Mock()
+        segments_result.scalars.return_value.all.return_value = [segment]
+
+        chapter_result = Mock()
+        chapter_result.scalar_one_or_none.return_value = None
+
+        book_result = Mock()
+        book_result.scalar_one_or_none.return_value = None
+
+        db = Mock()
+        db.execute.side_effect = [segments_result, chapter_result, book_result]
+        db.get.return_value = None
+        session_local_cls.return_value = db
+
+        events: list[str] = []
+        db.commit.side_effect = lambda: events.append("commit")
+        delay_mock.side_effect = lambda chapter_id: events.append(f"delay:{chapter_id}")
+
+        task_self = SimpleNamespace(
+            request=SimpleNamespace(id="task-1"),
+            retry=Mock(side_effect=AssertionError("retry should not be called")),
+        )
+        process_memoir_segments.run.__func__(task_self, "user-1", ["segment-1"])
+
+        self.assertIn("commit", events)
+        delay_events = [event for event in events if event.startswith("delay:")]
+        self.assertEqual(len(delay_events), 1)
+        self.assertGreater(events.index(delay_events[0]), events.index("commit"))