Add mission briefing system that displays when entering VR and requires
trigger pull to dismiss before gameplay begins. This prevents accidental
weapon firing and provides clear mission objectives to players.
## Key Features
- Mission brief displays on VR entry with objectives from directory.json
- Ship controls disabled during briefing (movement, rotation, weapons)
- Either controller trigger dismisses brief and starts game timer
- First trigger pull does not fire weapons, only dismisses briefing
- Subsequent trigger pulls fire weapons normally
## Implementation Details
- Added MissionBrief class with mesh-based UI parented to ship
- Ship class gains disableControls()/enableControls() methods
- New mission brief trigger observable bypasses normal shoot handling
- ControllerInput modified to allow triggers through when disabled
- Level1 orchestrates control flow: disable → show brief → enable
- Game timer and physics recording start only after dismissal
## Technical Changes
- controllerInput.ts: Allow trigger events when controls disabled
- ship.ts: Add control state tracking and mission brief observable
- level1.ts: Integrate mission brief into XR initialization flow
- missionBrief.ts: New class for displaying briefing with trigger detection
- Fixed property name mismatch in level selection event dispatch
- Added cache-busting for dev mode level loading
- Exposed LevelRegistry to window for debugging
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>