Restructure CLI entry point and RPC handler registration to improve maintainability:
- Introduce command registry pattern with CommandDefinition interface for consistent command structure
- Extract individual command modules (claude, codex, daemon, doctor, gemini, auth, connect, etc.)
- Move RPC handlers into separate feature modules (bash, files, git, directories, ripgrep, difftastic, slashCommands)
- Create shared RPC types and response helpers (rpcTypes.ts, rpcResponses.ts)
- Move SpawnSessionOptions and SpawnSessionResult to rpcTypes for proper type organization
- Simplify index.ts to minimal entrypoint using command registry
- Update imports in apiMachine.ts and daemon/run.ts to use rpcTypes module
This enables:
- Better code organization by feature/command
- Easier testing of individual commands
- Safer RPC handler registration without side effects
- Clearer separation of concerns between routing and business logic