- playerstatus: look up screen by slug before UpsertDisplayState to pass UUID (not slug) and avoid FK violation
- router: switch display command route from authOnly to authScreen for proper permission enforcement
- display.go: remove redundant GetBySlug + requireScreenAccess (now handled by authScreen middleware), drop store dependency
- notifier: replace fmt.Sprintf %q with json.Marshal for correct JSON encoding of display command payload
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>