feat(normalsub): Implement flexible, path-based subscription URLs

Refactors the NormalSub feature to move away from a hardcoded `/sub/normal/` path and a restrictive single-word subpath. This change introduces support for multi-segment, slash-separated subpaths (e.g., `path/to/resource`), providing greater flexibility for creating descriptive and structured subscription URLs.

core/cli.py

@@ -586,8 +586,9 @@ def singbox(action: str, domain: str, port: int):
               help='Action to perform: start, stop, or edit_subpath')
 @click.option('--domain', '-d', required=False, help='Domain name for SSL (for start action)', type=str)
 @click.option('--port', '-p', required=False, help='Port number for NormalSub service (for start action)', type=int)
-@click.option('--subpath', '-sp', required=False, help='New subpath (alphanumeric, for edit_subpath action)', type=str)
+@click.option('--subpath', '-sp', required=False, help="New subpath (e.g., 'path' or 'path/to/resource', for edit_subpath action)", type=str)
 def normalsub(action: str, domain: str, port: int, subpath: str):
+    """Manage the NormalSub service."""
     try:
         if action == 'start':
             if not domain or not port: