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/ram-ttl.md

@@ -0,0 +1,55 @@
+---
+title: Set TTL on Cache Keys
+impact: HIGH
+impactDescription: Prevents unbounded memory growth
+tags: ttl, expiration, cache, memory
+description: Set TTL on Cache Keys
+alwaysApply: true
+---
+
+## Set TTL on Cache Keys
+
+Always set expiration times on cache keys to prevent unbounded memory growth.
+
+**Correct:** Set TTL at write time.
+
+**Python** (redis-py):
+```python
+# Good: TTL set atomically with the value
+redis.setex("cache:user:1001", 3600, user_json)
+
+# Good: For hashes, set TTL after
+redis.hset("session:abc", mapping=session_data)
+redis.expire("session:abc", 1800)
+```
+
+**Java** (Jedis):
+```java
+import redis.clients.jedis.params.SetParams;
+
+// Good: TTL set atomically with SetParams
+jedis.set("cachedItem:1", "fe8c357903ac9", new SetParams().ex(120));
+```
+
+**Incorrect:** Forgetting TTL on cache keys.
+
+**Python** (redis-py):
+```python
+# Risk: This key may live forever
+redis.set("cache:user:1001", user_json)
+```
+
+**Java** (Jedis):
+```java
+// Risk: This key may live forever
+jedis.set("cachedItem:1", "fe8c357903ac9");
+```
+
+**TTL strategies:**
+- Cache data: 1-24 hours depending on freshness requirements
+- Sessions: 30 minutes to 24 hours
+- Rate limiting: Seconds to minutes
+- Temporary locks: Seconds with automatic release
+
+Reference: [Redis EXPIRE](https://redis.io/commands/expire/)
+