feat(rmeets): require username on join, fix settings/background, add MI toolbar
- Enable prejoin page so users must enter a display name before joining
- Add requireDisplayName, SETTINGS_SECTIONS, disableVirtualBackground config
- Add floating Meeting Intelligence button with recordings/search links
- Add chat, settings, participants-pane to folk-jitsi-room toolbar
- Also includes: rDocs module expansion, tab-cache/view-history updates,
converter rewrites, MCP tool additions, OAuth fixes, backlog tasks
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>