refactor: rename projman-test-marketplace to projman-marketplace

- Remove empty marketplace.json placeholder file
- Rename projman-test-marketplace/ to projman-marketplace/
- Update marketplace metadata (name, displayName, description)
- Update all documentation references

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/TEST_EXECUTION_REPORT.md

@@ -396,7 +396,7 @@ projman/
 ### Test Infrastructure
 ```
 .claude-plugins/
-└── projman-test-marketplace/
+└── projman-marketplace/
     └── marketplace.json                (New)
 
 .env                                    (New, not committed)