broadcast config changes to google app windows

[timche]

Summary

• Added GoogleApp.getAllWindows() static method that returns the window for every live GoogleApp instance.
• config.onDidAnyChange in packages/app/ipc.ts now iterates those windows and sends config.configChanged to each, so open Google app windows stay in sync with config updates (previously only the main window and the recent-downloads popup received it).
• Renamed the GoogleApp.browserWindow property (and matching GoogleAppOptions key) to window for consistency with the new getAllWindows() API; updated all call sites in gmail/index.ts and menu.ts.

Test plan

• Open a Google app (e.g. Docs) in its own window, change a config value from Settings, confirm the Google app window receives the update without a reload.
• bun types:ci passes.

https://claude.ai/code/session_013sYiktrR1bBzwDnowF3S5G