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/_template.md

@@ -0,0 +1,52 @@
+---
+title: Clear, Action-Oriented Title (e.g., "Use Connection Pooling")
+impact: MEDIUM
+impactDescription: Brief quantified benefit (e.g., "Reduces connection overhead by 10x")
+tags: relevant, keywords, here
+description: Clear, Action-Oriented Title (e.g., "Use Connection Pooling")
+alwaysApply: true
+---
+
+## [Rule Title]
+
+[1-2 sentence explanation of the problem and why it matters. Focus on practical impact.]
+
+**Correct:** Description of the good approach.
+
+```python
+# Comment explaining why this is better
+pool = ConnectionPool(host='localhost', max_connections=50)
+redis = Redis(connection_pool=pool)  # Reuse connections
+result = redis.get('key')
+```
+
+---
+### Choose ONE of the following patterns:
+
+#### Pattern A: "Incorrect" (when alternative causes real harm)
+Use when the alternative causes race conditions, security issues, crashes, or significant performance problems.
+
+**Incorrect:** Description of the problematic approach.
+
+```python
+# Comment explaining what makes this problematic
+redis = Redis(host='localhost')  # New connection per request - 10x overhead
+result = redis.get('key')
+```
+
+#### Pattern B: "When to use" (for feature introductions)
+Use when not using the feature is a valid choice for many use cases.
+
+**When to use:**
+- Scenario where this approach is beneficial
+- Another scenario where it helps
+
+**When NOT needed:**
+- Scenario where the simpler approach is fine
+- Another scenario where this adds unnecessary complexity
+
+---
+
+[Optional: Additional context, edge cases, or trade-offs]
+
+Reference: [Redis Docs](https://redis.io/docs/)