docs: add RLM integration plan for AI Dark Factory

Create comprehensive plan for leveraging RLM in the dark factory
orchestrator. Covers per-agent VM isolation, snapshot-based state
management, recursive LLM calls, and unified budget enforcement.

Three-phase implementation over 6 weeks:
- Phase 1: RLM integration layer (terraphim_orchestrator_rlm crate)
- Phase 2: Enhanced agent capabilities (snapshots, recursive LLM)
- Phase 3: Advanced features (VM pools, cross-agent handoff)

Refs #426

Author: AlexMikhalev