feat: add dashboard menu, [DEFAULT_DIR] placeholder, live dir validation, and backup security

- Add Dashboard as first submenu entry in component manifest
- Add [DEFAULT_DIR] placeholder to PlaceholderResolver for portable profiles
- Add live AJAX directory permission checking on backup_dir field changes
- Add web-accessible warning badge on backup download buttons
- Auto-create .htaccess protection in web-accessible backup dirs on profile save
- Auto-create .htaccess protection at backup time in both engines
- Add checkDir AJAX endpoint for real-time directory validation
- Fix script.php warnMissingLicenseKey running on uninstall

source/script.php

@@ -203,8 +203,10 @@ class Pkg_MokoJoomBackupInstallerScript
 			}
 		}
 
-		// Warn if no license key configured
-		$this->warnMissingLicenseKey();
+		// Warn if no license key configured (skip on uninstall)
+		if ($type !== 'uninstall') {
+			$this->warnMissingLicenseKey();
+		}
 	}
 
 	/**