Security fix: Remove webshell patterns and exclude test PHP files

- Replaced btoa/atob encoding with safe Map storage
- Replaced innerHTML with DOM manipulation
- Excluded demorepo1 folder containing test webshells
- Fixes false positive antivirus detections

Author: r

.vscodeignore

@@ -7,4 +7,6 @@ vsc-extension-quickstart.md
 **/tsconfig.json
 **/.eslintrc.json
 **/*.map
-**/*.ts
+**/*.ts
+demorepo1/**
+media/sidebar-backup.js