ADR-002: V4 Instruct-Only GRPO — revises dual-model plan based on model repo audit

Add comprehensive investigation report — performance audit, unexplored alternatives, literature-backed recommendations

Add session checkpoint: v3 launch decision with full context

Add v3 thinking control patch - task-aware system prompts + think efficiency reward

docs: add ADR-001 next steps with detailed execution plans

docs: add project documentation