security: 安全审计修复 - API Key清理 + JWT改为HttpOnly Cookie

- API Key: run.md/.env/seed_model_providers.sql 中明文Key替换为占位符
- 认证: JWT从localStorage迁移到HttpOnly Cookie，移除后端body返回token
- 前端: api.ts/knowledge/page.tsx/auth.ts 全面改用Cookie认证
- postcss XSS: package.json添加overrides强制升级到8.5.15
- gitignore: 添加server/.env和.env排除规则
- lint: 移除tenant.go中未使用的roleKey常量
- 文档: 新增docs/security-audit-report.md和hardware-requirements.md

apps/web/package.json

@@ -46,5 +46,8 @@
     "tailwindcss": "^4",
     "typescript": "^5",
     "typescript-eslint": "^8.62.0"
+  },
+  "overrides": {
+    "postcss": ">=8.5.10"
   }
-}
+}