fix: tolerant readonly filesystem for copy favicon to static dir

backend/config.py

@@ -310,6 +310,12 @@ if frontend_favicon.exists():
         shutil.copyfile(frontend_favicon, STATIC_DIR / "favicon.png")
     except PermissionError:
         logging.error(f"No write permission to {STATIC_DIR / 'favicon.png'}")
+    except OSError as e:
+        if e.errno == 30:  # Read-only file system
+            logging.error(f"Read-only file system: {STATIC_DIR / 'favicon.png'}")
+        else:
+            logging.error(f"OS error occurred: {e}")
+
 else:
     logging.warning(f"Frontend favicon not found at {frontend_favicon}")