feat(xiaomi-mimo): server-assisted desktop login, five account clusters, v2.6 models

Reproduce the MiMo Desktop login surface server-side so headless/Docker
deployments can link a Xiaomi account without the Desktop client. The
account session (passToken) is captured during the proxied login and
stored per connection.

- Five account clusters (cn/sgp/ams/ru/in): per-region mimo-server host
  and SSO sid, unknown region falls back to sgp
- mimo-v2.6-pro/flash/pro-ultraspeed dual-route models: account-service
  route when desktop credentials exist, cloud API (sk- key) otherwise;
  drops obsolete mimo-x-*-preview ids
- Desktop ServiceTokenManager 2-phase handshake (single serviceLogin with
  target sid, raw 64-bit nonce preserved), per-region session cache
- reasoning_effort bridged to output_config.effort; i18n runtime now
  observes characterData mutations so React text rewrites get translated
- Security hardening on the login proxy: session travels only in the
  httpOnly cookie (never in the URL), proxy branch requires dashboard
  auth, authorization/proxy-authorization never forwarded upstream, and
  upstream Set-Cookie is not replayed onto the app origin

public/i18n/literals/zh-CN.json

@@ -1390,5 +1390,30 @@
   "⚠️ Risk Notice: This provider uses a subscription/OAuth session not officially licensed for proxy/router use. Account may be restricted or banned. Use at your own risk.": "⚠️ 风险提示：此提供商使用的订阅/OAuth 会话未获官方授权用于代理/路由器使用。账户可能被限制或封禁。使用风险自负。",
   "✓ Confirm Add": "✓ 确认添加",
   "📝 Configure providers in dashboard or use environment variables": "📝 在仪表盘中配置提供商或使用环境变量",
-  "🔐 OAuth required. Add now and authenticate after Apply; tool list will be discovered after first connect.": "🔐 需要 OAuth。立即添加并在应用后认证；工具列表将在首次连接后自动发现。"
+  "🔐 OAuth required. Add now and authenticate after Apply; tool list will be discovered after first connect.": "🔐 需要 OAuth。立即添加并在应用后认证；工具列表将在首次连接后自动发现。",
+  "Reading local MiMo Desktop credentials...": "正在读取本地 MiMo 桌面版凭证...",
+  "Desktop Plan · Local credentials": "Desktop Plan · 本地凭证",
+  "This account is already connected (no need to import again)": "该账号已连接（无需重复导入）",
+  "Untested": "未测试",
+  "Re-sync local credentials": "重新同步本地凭证",
+  "Connect with local credentials": "使用本地凭证连接",
+  "or": "或",
+  "Browser Login": "网页登录",
+  "No Desktop required": "无需桌面客户端",
+  "Weekly quota": "周额度",
+  "Waiting for login...": "等待登录中...",
+  "Reopen login window": "重新打开登录窗口",
+  "Choose cluster & sign in": "选择集群并登录",
+  "Login session expired — please retry.": "登录会话已过期，请重试。",
+  "Failed to save credentials": "保存凭据失败",
+  "Import failed": "导入失败",
+  "No local Desktop credentials found": "未检测到本地桌面凭证",
+  "You can still sign in via browser — no Desktop client needed.": "仍可通过网页登录，无需桌面客户端。",
+  "Select account cluster": "选择小米账号集群",
+  "Choose the region cluster of your Xiaomi account:": "请选择你的小米账号所在地区集群：",
+  "China (Mainland)": "中国大陆",
+  "Singapore": "新加坡",
+  "Europe · Amsterdam": "欧洲 · 阿姆斯特丹",
+  "Russia": "俄罗斯",
+  "India": "印度"
 }