chore: add update auth config defaults

packaging/default_config/app_config.json

@@ -3,5 +3,10 @@
   "output_quality": 95,
   "output_dir": "",
   "last_garment_dir": "",
-  "last_print_dir": ""
+  "last_print_dir": "",
+  "last_template": "",
+  "last_batch_mode": "full_combo",
+  "update_source": "",
+  "update_user": "",
+  "update_pass": ""
 }

src/services/config_service.py

@@ -11,7 +11,9 @@ DEFAULT_CONFIG = {
     "last_print_dir": "",
     "last_template": "",       # name of the last-selected template
     "last_batch_mode": "full_combo",  # BatchMode value of the last-used mode
-    "update_source": "",       # LAN folder holding manifest.json (empty = no update check)
+    "update_source": "",       # HTTP(S) manifest source (empty = no update check)
+    "update_user": "",         # HTTP Basic Auth user (empty = anonymous)
+    "update_pass": "",         # HTTP Basic Auth password (empty = anonymous)
 }
 
 _CONFIG_FILENAME = "app_config.json"