## What changed
- Represent whether realtime is active as a persisted world-state section.
- Emit start and end instructions from world-state transitions, including when
reconstructing context after resume.
- Retain existing realtime start fragments and avoid emitting another start when
custom instructions change while realtime remains active.
## Testing
- Add snapshot coverage for absent, unknown, active, and inactive realtime state
transitions.
- Cover realtime start and end updates plus resuming with changed custom start
instructions.
GitOrigin-RevId: ec670b8132b0f1c9317738bfdeb272069927d91d
pakrym-oai
b9680065b0