fix: clean up Phase 1/2 commit issues

- Remove duplicate HTTP_STATUS/NETWORK exports in constants.js
- Remove unused responseHelpers import from server.js
- Remove backup file and doc artifacts from tracking
- Update .gitignore to prevent re-adding bloat files

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

dashcaddy-installer/.gitignore

@@ -3,3 +3,5 @@ dist/
 *.log
 .DS_Store
 Thumbs.db
+LOGO_INTEGRATION.md
+README-TESTER.txt