- Move RPC files to modes/rpc/ directory
- Add properly typed RpcCommand and RpcResponse types
- Expose full AgentSession API via RPC commands:
- State: get_state
- Model: set_model, cycle_model, get_available_models
- Thinking: set_thinking_level, cycle_thinking_level
- Queue: set_queue_mode
- Compaction: compact, set_auto_compaction
- Bash: bash, abort_bash
- Session: get_session_stats, export_html, switch_session, branch, etc.
- Add RpcClient class for programmatic access
- Rewrite tests to use RpcClient instead of raw process spawning
- All commands support optional correlation ID for request/response matching
