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/.cursor-plugin/plugin.json

@@ -0,0 +1,14 @@
+{
+  "name": "redis-development",
+  "version": "1.0.0",
+  "description": "Redis development best practices — data structures, query engine, vector search, caching, and performance optimization",
+  "author": {
+    "name": "Redis",
+    "email": "support@redis.com"
+  },
+  "homepage": "https://redis.io",
+  "repository": "https://github.com/redis/agent-skills",
+  "license": "MIT",
+  "keywords": ["redis", "database", "caching", "vector-search", "performance", "best-practices"],
+  "logo": "assets/logo.png"
+}