refactor: consolidate file path validation patterns and support scoped packages

- Extract file path validation regex into ValidationPatterns::FILE_PATH_PATTERN constant
- Add filePathRules() and filePathMessages() helper methods for reusable validation
- Extend allowed characters from [a-zA-Z0-9._\-/] to [a-zA-Z0-9._\-/~@+] to support:
  - Scoped npm packages (@org/package)
  - Language-specific directories (c++, rust+)
  - Version markers (v1~, build~)
- Replace duplicate inline regex patterns across multiple files
- Add tests for paths with @ symbol and tilde/plus characters

app/Jobs/ApplicationDeploymentJob.php

@@ -3929,7 +3929,7 @@ COPY ./nginx.conf /etc/nginx/conf.d/default.conf");
 
     private function validatePathField(string $value, string $fieldName): string
     {
-        if (! preg_match('/^\/[a-zA-Z0-9._\-\/]+$/', $value)) {
+        if (! preg_match(\App\Support\ValidationPatterns::FILE_PATH_PATTERN, $value)) {
             throw new \RuntimeException("Invalid {$fieldName}: contains forbidden characters.");
         }
         if (str_contains($value, '..')) {