feat(phase1): 完成 Repository 测试和 Redis 会话管理

Task 2: 完成 Repository 层测试
- 实现 CaseLibraryRepositoryTest (6 个测试)
- 实现 ApiDocumentRepositoryTest (7 个测试)
- 所有 Repository 测试通过 (19/19)

Task 3: 完成 Redis 会话管理
- 创建 SessionContext 和 ToolCall 数据类
- 创建 SessionManager 接口
- 实现 RedisSessionManager (基于 Redis 的会话管理)
- 创建 SessionConfiguration (Redis 序列化配置)
- 实现 RedisSessionManagerTest (8 个测试全部通过)

测试结果：
- ApiDocumentRepositoryTest: 7/7 通过
- CaseLibraryRepositoryTest: 6/6 通过
- DiagnosisRecordRepositoryTest: 6/6 通过
- RedisSessionManagerTest: 8/8 通过
- 总计: 27/27 测试通过

功能特性：
- 会话创建、查询、更新、删除
- 会话过期时间管理
- 工具调用记录追踪
- 会话状态管理
- 基于 Redis 的分布式会话存储

Progress: 20/33 tasks completed (61%)

.claude/skills/handoff/SKILL.md

@@ -0,0 +1,16 @@
+  ---
+  name: handoff
+  description: Compact the current conversation into a handoff document for another agent to pick up.
+  argument-hint: "What will the next session be used for?"
+  disable-model-invocation: true
+  ---
+  
+  Write a handoff document summarising the current conversation so a fresh agent can continue the work. Save to the temporary directory of the user's OS - not the current workspace.
+  
+  Include a "suggested skills" section in the document, which suggests skills that the agent should invoke.
+  
+  Do not duplicate content already captured in other artifacts (PRDs, plans, ADRs, issues, commits, diffs). Reference them by path or URL instead.
+  
+  Redact any sensitive information, such as API keys, passwords, or personally identifiable information.
+  
+  If the user passed arguments, treat them as a description of what the next session will focus on and tailor the doc accordingly.