chore: register repo with Custodian State Hub + add CLAUDE.md

- Register marki-docx under markitect domain (repo ID 75d31180)
- Add CLAUDE.md with full session protocol, workplan convention (ADR-001),
  First Session Protocol, and contribution/SBOM tracking instructions
- Ignore .claude/ local state directory

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -1,3 +1,6 @@
+# Claude Code local state
+.claude/
+
 # ---> Python
 # Byte-compiled / optimized / DLL files
 __pycache__/