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/json-partial-updates.md

@@ -0,0 +1,49 @@
+---
+title: Use JSON Paths for Partial Updates
+impact: MEDIUM
+impactDescription: Avoids fetching and rewriting entire documents
+tags: json, partial-updates, paths, atomic
+description: Use JSON Paths for Partial Updates
+alwaysApply: true
+---
+
+## Use JSON Paths for Partial Updates
+
+Use JSON path syntax to update specific fields without fetching the entire document.
+
+**Correct:** Use JSON paths for targeted updates.
+
+```python
+# Store JSON document
+redis.json().set("user:1001", "$", {
+    "name": "Alice",
+    "email": "alice@example.com",
+    "preferences": {"theme": "dark", "notifications": True}
+})
+
+# Update nested field without fetching entire document
+redis.json().set("user:1001", "$.preferences.theme", "light")
+
+# Get specific field
+theme = redis.json().get("user:1001", "$.preferences.theme")
+
+# Increment numeric field atomically
+redis.json().numincrby("user:1001", "$.preferences.volume", 5)
+
+# Append to array
+redis.json().arrappend("user:1001", "$.tags", "premium")
+```
+
+**Incorrect:** Storing JSON as a string and parsing client-side.
+
+```python
+# Bad: Loses queryability and atomic updates
+redis.set("user:1001", json.dumps(user_data))
+
+# Must fetch, parse, modify, serialize, and rewrite
+data = json.loads(redis.get("user:1001"))
+data["preferences"]["theme"] = "light"
+redis.set("user:1001", json.dumps(data))
+```
+
+Reference: [Redis JSON Path](https://redis.io/docs/latest/develop/data-types/json/path/)