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/_contributing.md

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+# Writing Guidelines for Redis Rules
+
+Guidelines for creating effective Redis best practice rules for AI agents and LLMs.
+
+## Key Principles
+
+### 1. Concrete Patterns
+
+Show exact code transformations. Avoid abstract advice.
+
+**Good:** "Use `SCAN` instead of `KEYS *` for iteration"
+**Bad:** "Design efficient queries"
+
+### 2. Problem-First Structure
+
+Show the correct pattern first, then the incorrect one. This helps agents understand what to do and what to avoid.
+
+```markdown
+**Correct:** Description of good approach.
+
+[good example]
+
+**Incorrect:** Description of problematic approach.
+
+[bad example]
+```
+
+### 3. Practical Impact
+
+Include specific benefits. Helps agents prioritize.
+
+**Good:** "10x faster", "50% less memory", "Eliminates blocking"
+**Bad:** "Faster", "Better", "More efficient"
+
+### 4. Complete Examples
+
+Examples should be runnable or close to it.
+
+```python
+import redis
+
+# Include setup when needed for clarity
+pool = redis.ConnectionPool(host='localhost', max_connections=50)
+r = redis.Redis(connection_pool=pool)
+
+# Now show the pattern
+result = r.get('user:1001')
+```
+
+### 5. Semantic Naming
+
+Use meaningful names. Names carry intent for LLMs.
+
+**Good:** `user:1001:profile`, `order:items`, `cache:api:response`
+**Bad:** `key1`, `mykey`, `data`
+
+---
+
+## Code Standards
+
+### Language Tags
+
+- `python` - Python examples (preferred for Redis)
+- `javascript` - Node.js examples
+- `bash` - Redis CLI commands
+- (none) - Redis commands without language wrapper
+
+### Comments
+
+- Explain _why_, not _what_
+- Highlight performance implications
+- Point out common mistakes
+
+---
+
+## Impact Levels
+
+| Level | Improvement | Examples |
+|-------|-------------|----------|
+| **HIGH** | 5-100x | Missing indexes, connection issues, blocking commands |
+| **MEDIUM** | 2-5x | Suboptimal data structures, missing TTL |
+| **LOW** | Incremental | Advanced patterns, edge cases |
+
+---
+
+## Review Checklist
+
+Before submitting a rule:
+
+- [ ] Title is clear and action-oriented
+- [ ] Impact level matches the benefit
+- [ ] impactDescription includes quantification
+- [ ] Has at least 1 **Correct** example
+- [ ] Has at least 1 **Incorrect** example
+- [ ] Code uses semantic naming
+- [ ] Comments explain _why_
+- [ ] Reference links included