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/lib/api/providers.ts

@@ -38,6 +38,14 @@ export const providersApi = {
     return await invoke("delete_provider", { id, app: appId });
   },
 
+  /**
+   * Remove provider from live config only (for additive mode apps like OpenCode)
+   * Does NOT delete from database - provider remains in the list
+   */
+  async removeFromLiveConfig(id: string, appId: AppId): Promise<boolean> {
+    return await invoke("remove_provider_from_live_config", { id, app: appId });
+  },
+
   async switch(id: string, appId: AppId): Promise<boolean> {
     return await invoke("switch_provider", { id, app: appId });
   },