feat(mcp): add import button to import MCP servers from apps

- Add import_mcp_from_apps command that reuses existing import logic
- Add Import button in MCP panel header (consistent with Skills)
- Fix import count to only return truly new servers (not already in DB)
- Update translations for import success/no-import messages (zh/en/ja)

src-tauri/src/commands/mcp.rs

@@ -192,3 +192,13 @@ pub async fn toggle_mcp_app(
     let app_ty = AppType::from_str(&app).map_err(|e| e.to_string())?;
     McpService::toggle_app(&state, &server_id, app_ty, enabled).map_err(|e| e.to_string())
 }
+
+/// 从所有应用导入 MCP 服务器（复用已有的导入逻辑）
+#[tauri::command]
+pub async fn import_mcp_from_apps(state: State<'_, AppState>) -> Result<usize, String> {
+    let mut total = 0;
+    total += McpService::import_from_claude(&state).unwrap_or(0);
+    total += McpService::import_from_codex(&state).unwrap_or(0);
+    total += McpService::import_from_gemini(&state).unwrap_or(0);
+    Ok(total)
+}