refactor: normalize branch name handling and enhance auto mode settings merging

- Updated branch name normalization to align with UI conventions, treating "main" as null for consistency.
- Implemented deep merging of `autoModeByWorktree` settings to preserve existing entries during updates.
- Enhanced the BoardView component to persist max concurrency settings to the server, ensuring accurate capacity checks.
- Added error handling for feature rollback persistence in useBoardActions.

These changes improve the reliability and consistency of auto mode settings across the application.

apps/ui/src/components/views/board-view/hooks/use-board-actions.ts

@@ -553,6 +553,11 @@ export function useBoardActions({
         };
         updateFeature(feature.id, rollbackUpdates);
 
+        // Also persist the rollback so it survives page refresh
+        persistFeatureUpdate(feature.id, rollbackUpdates).catch((persistError) => {
+          logger.error('Failed to persist rollback:', persistError);
+        });
+
         // If server is offline (connection refused), redirect to login page
         if (isConnectionError(error)) {
           handleServerOffline();