chore: rename markitect_project to markitect-main across project

Finishes the in-progress rename so docs, configs, tests, and capability
manifests all reference the current repo name consistently. Fixes two
tests (test_roundtrip_consolidated.py, test_issue_140_roundtrip_simplified.py)
whose hardcoded cwd paths would have broken under the renamed directory.

Archival content under history/, reports/, and roadmap/eat-the-frog/, plus
derived artifacts (.venv_old/, node_modules/, asset_registry.json) are
intentionally left untouched.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

capabilities/release-management/MIGRATION_PLAN.md

@@ -209,7 +209,7 @@ tests/
 ## 🎯 Detailed File Structure After Migration
 
 ```
-markitect_project/
+markitect-main/
 ├── capabilities/
 │   └── release-management/
 │       ├── README.md                              ✅ CREATED