fix: resolve UnboundLocalError when reverse proxy auth disabled

Move flask g and request imports to function scope so they're available
regardless of config.config_allow_reverse_proxy_header_login setting.

Author: crocodilestick

CONTRIBUTORS

@@ -312,7 +312,7 @@ Copyright (C) 2024-2026 Calibre-Web Automated contributors
 - zhiyue (1 commits)
 # Fork Contributors (crocodilestick/calibre-web-automated)
 
-- crocodilestick (919 commits)
+- crocodilestick (921 commits)
 - jmarmstrong1207 (73 commits)
 - demitrix (30 commits)
 - sirwolfgang (29 commits)

cps/__init__.py

@@ -244,6 +244,7 @@ def create_app():
     # Ensure a valid calibre_db session exists before handling each request
     @app.before_request
     def _cwa_ensure_db_session():
+        from flask import g, request
         from .cw_login import current_user
         from sqlalchemy import or_
         import time
@@ -257,7 +258,6 @@ def _cwa_ensure_db_session():
             This must run before any blueprint before_request handlers that access current_user.
             """
 
-            from flask import g, request
             from . import usermanagement
             user = usermanagement.load_user_from_reverse_proxy_header(request)
             if user: