fix: cleanup for plugin submission (tasks 9-13)

- Remove unused vault.delete() method in favor of trashFile()
- Replace \x00-\x1F with \u0000-\u001F for clearer regex syntax
- Verify no unused imports, variables, or scoping issues

All cleanup tasks verified with tsc --noUnusedLocals --noUnusedParameters

src/utils/path-utils.ts

@@ -65,7 +65,8 @@ export class PathUtils {
 		}
 
 		// Check for invalid characters (Windows restrictions)
-		const invalidChars = /[<>:"|?*\x00-\x1F]/;
+		// Invalid chars: < > : " | ? * and ASCII control characters (0-31)
+		const invalidChars = /[<>:"|?*\u0000-\u001F]/;
 		if (invalidChars.test(normalized)) {
 			return false;
 		}