feat: add official balance query for DeepSeek, StepFun, SiliconFlow, OpenRouter, Novita AI

Add a new "Official" (官方) template type in the usage query panel that
queries account balance via each provider's native API endpoint.
Follows the same zero-script pattern as Token Plan — Rust handles the
HTTP call, frontend auto-detects the provider from base URL.

Supported providers and endpoints:
- DeepSeek: GET /user/balance
- StepFun: GET /v1/accounts
- SiliconFlow: GET /v1/user/info (cn + com)
- OpenRouter: GET /api/v1/credits
- Novita AI: GET /v3/user/balance

src/i18n/locales/en.json

@@ -1091,8 +1091,10 @@
     "templateNewAPI": "NewAPI",
     "templateCopilot": "GitHub Copilot",
     "templateTokenPlan": "Token Plan",
+    "templateBalance": "Official",
     "copilotAutoAuth": "Auto OAuth authentication, no manual credentials needed",
     "tokenPlanHint": "Automatically uses the provider's API Key and Base URL to query Token Plan quota",
+    "balanceHint": "Automatically uses the provider's API Key to query account balance",
     "resetDate": "Reset date",
     "premiumRequests": "Premium Requests",
     "credentialsConfig": "Credentials",

src/i18n/locales/ja.json

@@ -1091,8 +1091,10 @@
     "templateNewAPI": "NewAPI",
     "templateCopilot": "GitHub Copilot",
     "templateTokenPlan": "Token Plan",
+    "templateBalance": "公式",
     "copilotAutoAuth": "OAuth 認証を自動使用、手動設定不要",
     "tokenPlanHint": "プロバイダーのAPI KeyとBase URLを使用してToken Planクォータを自動クエリ",
+    "balanceHint": "プロバイダーのAPI Keyを使用してアカウント残高を自動クエリ",
     "resetDate": "リセット日",
     "premiumRequests": "Premium リクエスト",
     "credentialsConfig": "認証情報",

src/i18n/locales/zh.json

@@ -1091,8 +1091,10 @@
     "templateNewAPI": "NewAPI",
     "templateCopilot": "GitHub Copilot",
     "templateTokenPlan": "Token Plan",
+    "templateBalance": "官方",
     "copilotAutoAuth": "自动使用 OAuth 认证，无需手动配置凭证",
     "tokenPlanHint": "自动使用供应商的 API Key 和 Base URL 查询 Token Plan 额度",
+    "balanceHint": "自动使用供应商的 API Key 查询账户余额",
     "resetDate": "重置日期",
     "premiumRequests": "Premium 请求",
     "credentialsConfig": "凭证配置",