refactor(api): TOML 配置 SSOT、统一错误契约、Auth/事务加固与可观测性 (#33)

配置 SSOT（TOML + .env）
统一错误契约
Auth 与事务边界
Redis / Celery 可靠性:业务 Redis（DB/0）与 Celery broker/backend（DB/1）显式拆分；连接池、sync client
可观测性（OpenTelemetry + LGTM）

api/.agents/skills/redis-development/rules/conn-timeouts.md

@@ -0,0 +1,41 @@
+---
+title: Configure Connection Timeouts
+impact: MEDIUM
+impactDescription: Improves connection resilience and failure recovery
+tags: timeouts, connections, reliability
+description: Configure Connection Timeouts
+alwaysApply: true
+---
+
+## Configure Connection Timeouts
+
+Configure appropriate timeout values to improve your application's connection resilience. While most Redis clients set default timeouts, choosing well-tuned values based on your application's usage patterns leads to better failure recovery.
+
+**Correct:** Set timeouts based on your application needs.
+
+```python
+r = redis.Redis(
+    host='localhost',
+    socket_timeout=5.0,         # Read/write timeout - tune based on expected operation time
+    socket_connect_timeout=2.0,  # Connection timeout - shorter for fast failure detection
+    retry_on_timeout=True        # Automatic retry on timeout
+)
+```
+
+**Incorrect:** Relying solely on defaults without considering your use case.
+
+```python
+# Not ideal: Default timeouts may not match your application's needs
+r = redis.Redis(host='localhost')
+
+# For example, if your app needs fast failure detection,
+# the default timeouts might be too generous
+```
+
+**Considerations:**
+- Set `socket_connect_timeout` shorter than `socket_timeout` for quick connection failure detection
+- For latency-sensitive apps, use tighter timeouts with retry logic
+- For batch operations, allow longer timeouts to complete large operations
+- Consider using health checks alongside timeouts for robust failure handling
+
+Reference: [Redis Client Configuration](https://redis.io/docs/latest/develop/clients/)