feat(orchestration): add CLAUDE.md shared brain for parallel agent coordination

.orchestration/CLAUDE.md

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+# CLAUDE.md
+
+# Shared Brain for Roo Code Agent Sessions
+
+## Project: AI-Native IDE – Week 1
+
+### Lessons Learned
+
+- PreHook enforces scope and intent validation.
+- PostHook logs AST diffs, content hashes, and mutation class.
+- Session IDs and contributor model must be tied dynamically to each agent instance.
+- Active intents are required for agent execution; context injection is mandatory.
+- Parallel agents must respect content hashes to prevent stale file overwrites.
+
+### Architectural Notes
+
+- Hooks isolated and composable.
+- agent_trace.jsonl stores intent → file → hash → mutation_class.
+- Future: integrate real Git SHA for vcs.revision_id.
+- Future: append lessons automatically when linter/test fails.