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>

.claude-plugins/projman-marketplace/marketplace.json

@@ -1,8 +1,8 @@
 {
-  "name": "projman-test-marketplace",
+  "name": "projman-marketplace",
   "version": "1.0.0",
-  "displayName": "Projman Test Marketplace",
-  "description": "Local marketplace for testing the Projman plugin",
+  "displayName": "Projman Marketplace",
+  "description": "Marketplace for Projman project management plugins",
   "author": "Bandit Labs",
   "plugins": [
     {