Make guest room controls honestly read-only

[minglong51]

Summary

• announce leash, bowl, ball, and pet controls as disabled for guests
• route guest input before owner-only busy, night, pointer, and animation behavior
• remove hidden sun, moon, and rug hotspots from the settled accessibility tree without losing fade-outs

Verification

• uv run --extra dev pytest tests/test_guest_mode.py tests/test_voice_client.py (19 passed)
• design-doc structure and audit passed
• denylist check passed
• browser: disabled controls announced, busy/night taps return the guest explanation, dog stroking does not start, zero action requests, no console errors
• browser: sun, moon, and rug fade out before becoming hidden