Admin panel redesign:
- Rebuild frontend from mockup with Discord-style dark theme
- Stat cards, section cards, role badges, modal system, toast notifications
- All 7 sections: Dashboard, Users, Channels, Audit Log, Settings, Backups, Updates
- Modals replace confirm()/prompt() for all destructive actions
Live server logs (new):
- RingBuffer + MultiHandler tees slog to stdout AND in-memory buffer
- SSE endpoint at /admin/api/logs/stream streams logs in real-time
- Log viewer with level filters (DEBUG/INFO/WARN/ERROR), search,
auto-scroll, pause/resume, copy all, clear
- Color-coded lines by level, source categorization from file paths
Audit log improvements:
- Search filter (actor, action, target, detail)
- Action type dropdown filter
- Copy All and Export CSV buttons
- Instant client-side re-filtering
Console output:
- Switch from JSON to human-readable text format (slog.TextHandler)
- Move startup banner before init logs so it appears first
When no users exist, the admin panel shows a setup wizard instead of the
login form. Creates the first Owner account with a session token and
generates an unlimited invite code for onboarding other users. The setup
endpoint is locked out after the first user is created.
Also fixes the admin panel 404 by serving index.html directly for the
root path instead of delegating to http.FileServer.