feat(web): persist dashboard token in launcher config (#2304)

- add `launcher_token` to launcher config API/schema and save/load flow
- update dashboard token resolution order: env var -> launcher config -> random
- expose token source in startup logs and auth help metadata (including config path)
- add launcher token input to the config page and wire frontend form/API updates
- update login help/i18n copy and extend backend tests for new token-source behavior

web/frontend/src/api/launcher-auth.ts

@@ -17,6 +17,7 @@ export async function postLauncherDashboardLogin(
 export type LauncherAuthTokenHelp = {
   env_var_name: string
   log_file?: string
+  config_file?: string
   tray_copy_menu: boolean
   console_stdout: boolean
 }

web/frontend/src/api/system.ts

@@ -11,6 +11,7 @@ export interface LauncherConfig {
   port: number
   public: boolean
   allowed_cidrs: string[]
+  launcher_token: string
 }
 
 export interface SystemVersionInfo {