chore: 发布前准备 — 版本号统一 + 安全加固 + 死组件清理

- Cargo.toml workspace version 0.1.0 → 0.9.0-beta.1
- CSP 添加 object-src 'none' 防止插件注入
- .env.example 补充 SaaS 关键环境变量模板
- 移除已废弃的 SkillMarket.tsx 组件

desktop/src-tauri/tauri.conf.json

@@ -21,7 +21,7 @@
       }
     ],
     "security": {
-      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; font-src 'self'; img-src 'self' asset: https://asset.localhost data: blob:; connect-src ipc: http://ipc.localhost http://localhost:* https://*; frame-ancestors 'none'; base-uri 'self'; form-action 'self'"
+      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; font-src 'self'; img-src 'self' asset: https://asset.localhost data: blob:; connect-src ipc: http://ipc.localhost http://localhost:* https://*; object-src 'none'; frame-ancestors 'none'; base-uri 'self'; form-action 'self'"
     }
   },
   "bundle": {