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>

tests/test_issue_140_roundtrip_simplified.py

@@ -30,7 +30,7 @@ class TestActualRoundtripBehavior:
         cmd = ["python", "-m", "markitect.cli"] + args
         result = subprocess.run(
             cmd,
-            cwd="/home/worsch/markitect_project",
+            cwd="/home/worsch/markitect-main",
             capture_output=True,
             text=True
         )