Implements runtime configuration reload via POST /api/v1/organism/reload:
- StreamPump.reload_config() re-reads organism.yaml
- Adds new listeners, removes old ones, updates changed ones
- System listeners (system.*) are protected from removal
- ReloadEvent emitted to notify WebSocket subscribers
- ServerState.reload_config() refreshes agent runtime state
14 new tests covering add/remove/update scenarios.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
