feat: Phase 1+2 — project setup and core infrastructure

- requirements.txt, config.yaml, .env, Dockerfile, docker-compose.yml
- app/core: config (YAML+env override), logging (JSON structured),
  exceptions (typed hierarchy), json_utils (Markdown fence stripping)
- app/clients: LLMClient ABC + ZhipuAIClient (run_in_executor),
  StorageClient ABC + RustFSClient (boto3 head_object for size check)
- app/main.py: FastAPI app with health endpoint and router registration
- app/core/dependencies.py: lru_cache singleton factories
- tests/conftest.py: mock_llm, mock_storage, test_app, client fixtures
- pytest.ini: asyncio_mode=auto
- 11 unit tests passing

.gitignore

@@ -0,0 +1,32 @@
+# ==========================================
+# 1. Maven/Java 构建产物 (一键忽略整个目录)
+# ==========================================
+target/
+*.class
+*.jar
+*.war
+*.ear
+
+# ==========================================
+# 2. IDE 配置文件
+# ==========================================
+.idea/
+.vscode/
+*.iml
+*.ipr
+*.iws
+
+# ==========================================
+# 3. 项目特定工具目录 (根据你的文件列表)
+# ==========================================
+# 忽略 Specifiy 工具生成的所有配置和脚本
+.specify/
+
+# 忽略 Claude 本地设置和技能文件
+.claude/
+
+# ==========================================
+# 4. 操作系统文件
+# ==========================================
+.DS_Store
+Thumbs.db