refactor(opencode): simplify API format selector

- Reduce npm package options from 10 to 4 core API formats (OpenAI, OpenAI Compatible, Anthropic, Google)
- Rename "AI SDK Package" to "API Format" in i18n (zh/en/ja)
- Remove check icon from Select dropdown items for cleaner UI

src/i18n/locales/en.json

@@ -461,9 +461,9 @@
     "configReplaceFailed": "Config replace failed: {{error}}"
   },
   "opencode": {
-    "npmPackage": "AI SDK Package",
-    "selectPackage": "Select a package",
-    "npmPackageHint": "Select the npm package for communicating with the AI service",
+    "npmPackage": "API Format",
+    "selectPackage": "Select API format",
+    "npmPackageHint": "Select the API format for the AI service",
     "baseUrl": "Base URL",
     "baseUrlHint": "Custom API endpoint URL",
     "models": "Models",

src/i18n/locales/ja.json

@@ -461,9 +461,9 @@
     "configReplaceFailed": "設定の置換に失敗しました: {{error}}"
   },
   "opencode": {
-    "npmPackage": "AI SDK パッケージ",
-    "selectPackage": "パッケージを選択",
-    "npmPackageHint": "AI サービスとの通信に使用する npm パッケージを選択",
+    "npmPackage": "API フォーマット",
+    "selectPackage": "API フォーマットを選択",
+    "npmPackageHint": "AI サービスの API フォーマットを選択",
     "baseUrl": "Base URL",
     "baseUrlHint": "カスタム API エンドポイント URL",
     "models": "モデル設定",

src/i18n/locales/zh.json

@@ -461,9 +461,9 @@
     "configReplaceFailed": "配置替换失败: {{error}}"
   },
   "opencode": {
-    "npmPackage": "AI SDK 包",
-    "selectPackage": "选择一个包",
-    "npmPackageHint": "选择用于与 AI 服务通信的 npm 包",
+    "npmPackage": "接口格式",
+    "selectPackage": "选择接口格式",
+    "npmPackageHint": "选择 AI 服务的 API 接口格式",
     "baseUrl": "Base URL",
     "baseUrlHint": "自定义 API 端点地址",
     "models": "模型配置",