Fix Paperless login redirect issue

- Configure LOGIN_REDIRECT_URL and LOGOUT_REDIRECT_URL to /paperless/
- Set proper cookie paths for session isolation (/paperless/ instead of /)
- Use environment variables for redirect URLs in paperless_custom_settings.py
- Add PAPERLESS_URL and PAPERLESS_FORCE_SCRIPT_NAME to env template
- Ensure FORCE_SCRIPT_NAME respects environment variable

This fixes the issue where logging into Paperless redirects to the root Django
app instead of staying within the Paperless scope. The docker-compose.yml
already has the correct environment variables set.

paperless/paperless_custom_settings.py

@@ -10,9 +10,18 @@ SESSION_COOKIE_NAME = 'paperless_sessionid'
 # Also change CSRF cookie name for good measure
 CSRF_COOKIE_NAME = 'paperless_csrftoken'
 
-# Ensure cookies are scoped to avoid conflicts
-SESSION_COOKIE_PATH = '/'
-CSRF_COOKIE_PATH = '/'
+# Scope cookies to Paperless path to avoid conflicts
+SESSION_COOKIE_PATH = '/paperless/'
+CSRF_COOKIE_PATH = '/paperless/'
 
 # Different secret key salt to ensure session isolation
-SESSION_COOKIE_SALT = 'paperless.sessions'
+SESSION_COOKIE_SALT = 'paperless.sessions'
+
+# Fix login redirect to stay within Paperless scope  
+# Use environment variable if set, otherwise default to /paperless/
+LOGIN_REDIRECT_URL = os.getenv('PAPERLESS_LOGIN_REDIRECT_URL', '/paperless/')
+LOGOUT_REDIRECT_URL = os.getenv('PAPERLESS_LOGOUT_REDIRECT_URL', '/paperless/')
+LOGIN_URL = '/paperless/accounts/login/'
+
+# Ensure Force Script Name for proper URL handling behind proxy
+FORCE_SCRIPT_NAME = os.getenv('PAPERLESS_FORCE_SCRIPT_NAME', '/paperless')