fix: Views tabs show 1 view in other boards

[Xavier-Charles]

Problem Summary

When navigating from the main page "/" (showing 12 subscribed views) to another view like "/ethereum", the subscribedViews count dropped from 12 to 1. Root Cause: In [useView.ts:281], when addViewToCache is called for a subscribed view, it calls:

dispatch(viewsStore.updateSubscribedViewsCache([viewPreview]));

The updateSubscribedViewsCache reducer was designed to replace the entire cache with whatever array is passed to it. So passing a single-item array [viewPreview] wiped out all 11 other subscribed views.

Fix

Created a new Redux action addOrUpdateSubscribedView that:

• Takes a single view (not an array)
• Merges it into the existing cache instead of replacing
• Preserves all other views in the cache
  Changed useView.ts:281 to use the new action:

dispatch(viewsStore.addOrUpdateSubscribedView(viewPreview));

This preserves the original updateSubscribedViewsCache behavior (used to sync full server state) while fixing the single-view update case.

Also added and updated tests