chore: bump version to v2026.4.348 and update changelog}
- Bump version from v2026.4.346 to v2026.4.348 in package.json and all doc footers
- Add AI config fields to p3xrs.json: aiEnabled, aiUseOwnKey, groqApiKeyReadonly
- Expand README AI settings docs with routing options, config table, and readonly mode
- Defer Electron language menu until iframe is ready via new p3x-iframe-ready IPC event
- Add iframeReady flag to global state and conditionally render language submenu
- Make createWindow async and move mainMenu() call after BrowserWindow setup
- Fix setTimeout leak in onload.mjs by assigning to p3xSetLanguageWaiter
- Set iframeReady=true in setLanguage to ensure menu rebuilds on language change
- Update dependencies: p3x-redis-ui-material ^2026.4.346, p3x-redis-ui-server ^2026.4.309
- Update changelog prompt template for v2026.4.348
- Add v2026.4.348 changelog entry with AI routing and language menu fixes