🐛 fix(models sync): send correct overwrite payload and drop fallback

Ensure UpstreamConflictModal submits { overwrite: payload, locale } instead of spreading an array into an object
Remove numeric-key fallback from applyUpstreamOverwrite for simpler and explicit logic
Effect: selected fields are now actually updated; success message shows updated model count
Refs: backend SyncUpstreamModels expects overwrite: overwriteField[]

web/src/components/table/models/ModelsActions.jsx

@@ -245,7 +245,7 @@ const ModelsActions = ({
         conflicts={conflicts}
         onSubmit={async (payload) => {
           return await applyUpstreamOverwrite?.({
-            ...payload,
+            overwrite: payload,
             locale: syncLocale,
           });
         }}