fix: Refactor to store absolute base URL without trailing slash

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Marcel Klehr <mklehr@gmx.net>

Author: marcelklehr

ex_app/lib/agent.py

@@ -64,7 +64,7 @@ async def get_absolute_base_url(nc: AsyncNextcloudApp) -> str:
 			))['absolute_url'].rstrip('/')
 		except Exception as e:
 			print(f"Could not resolve absolute Nextcloud URL, falling back to endpoint: {e}")
-			return nc.app_cfg.endpoint
+			_absolute_base_url = nc.app_cfg.endpoint.rstrip('/')
 	return _absolute_base_url