fix(opencode): fix add/remove provider flow and toast messages

- Create separate removeFromLiveConfig API for additive mode apps
  (remove only removes from live config, not database)
- Fix useSwitchProviderMutation to invalidate opencodeLiveProviderIds
  cache so button state updates correctly after add operation
- Show appropriate toast messages:
  - Add: "已添加到配置" / "Added to config"
  - Remove: "已从配置移除" / "Removed from config"
- Add i18n texts for addToConfigSuccess and removeFromConfigSuccess

src/i18n/locales/en.json

@@ -137,6 +137,8 @@
     "providerSaved": "Provider configuration saved",
     "providerDeleted": "Provider deleted successfully",
     "switchSuccess": "Switch successful!",
+    "addToConfigSuccess": "Added to config",
+    "removeFromConfigSuccess": "Removed from config",
     "switchFailedTitle": "Switch failed",
     "switchFailed": "Switch failed: {{error}}",
     "autoImported": "Default provider created from existing configuration",

src/i18n/locales/ja.json

@@ -137,6 +137,8 @@
     "providerSaved": "プロバイダー設定を保存しました",
     "providerDeleted": "プロバイダーを削除しました",
     "switchSuccess": "切り替え成功！",
+    "addToConfigSuccess": "設定に追加しました",
+    "removeFromConfigSuccess": "設定から削除しました",
     "switchFailedTitle": "切り替えに失敗しました",
     "switchFailed": "切り替えに失敗しました: {{error}}",
     "autoImported": "既存設定からデフォルトプロバイダーを自動作成しました",

src/i18n/locales/zh.json

@@ -137,6 +137,8 @@
     "providerSaved": "供应商配置已保存",
     "providerDeleted": "供应商删除成功",
     "switchSuccess": "切换成功！",
+    "addToConfigSuccess": "已添加到配置",
+    "removeFromConfigSuccess": "已从配置移除",
     "switchFailedTitle": "切换失败",
     "switchFailed": "切换失败：{{error}}",
     "autoImported": "已从现有配置创建默认供应商",