refactor: 统一 DB/Redis 配置为 DSN 模式 + 移除 Helm/K8s 部署

- DatabaseConfig: Host/Port/User/Password/Name/DBName/SSLMode → 单个 DSN 字段
- RedisConfig: Host/Port/Password/DB/URL → 单个 DSN 字段
- 环境变量: GOCHAT_DATABASE_* (7个) → GOCHAT_DATABASE_DSN, GOCHAT_REDIS_* (5个) → GOCHAT_REDIS_DSN
- validator.go: DSN URL 解析校验 (scheme + host)
- redis.go: redis.ParseURL(cfg.DSN) 直连
- 所有 docker-compose / CI / shell 脚本 / .env 同步更新
- 删除 deploy/helm/ 整个目录 (20个文件)
- CI 删除 helm-validate / deploy-staging / deploy-production 三个 job
- 文档同步更新 (README, 架构设计, PRD, 滚动升级)

docs/ops/01-rolling-upgrade.md

@@ -39,33 +39,17 @@ curl -f http://gochat-green:3000/health
 docker compose -f docker-compose.prod.yml stop gochat
 ```
 
-### Step 4: K8s Rolling Update
-```bash
-# Kubernetes handles rolling updates automatically via Deployment strategy
-kubectl set image deployment/gochat gochat=gochat/gochat:${NEW_VERSION}
-kubectl rollout status deployment/gochat
-```
-
-K8s config (in Helm chart):
-- maxSurge: 1 (one extra pod during rollout)
-- maxUnavailable: 0 (no pods allowed to be unavailable)
-- readinessProbe: /ready endpoint
-- livenessProbe: /live endpoint
-
-### Step 5: Verification
-1. Smoke test: hit /health, /ready endpoints
+### Step 4: Verification
+1. Smoke test: hit /health endpoint
 2. Check logs for errors: `docker compose logs gochat --since 5m`
 3. Verify metrics: Prometheus dashboard should show normal traffic
 4. Monitor for 15 minutes before finalizing
 
-### Step 6: Rollback (if needed)
+### Step 5: Rollback (if needed)
 ```bash
 # Docker Compose rollback
 docker compose -f docker-compose.prod.yml exec gochat /app/gochat migrate down ${N}
 docker compose -f docker-compose.prod.yml up -d --no-deps gochat-${OLD_VERSION}
-
-# K8s rollback
-kubectl rollout undo deployment/gochat
 ```
 
 ## Migration Compatibility Rules