Remove redundant Catalog tab from store page

[zortos293]

This PR removes the redundant Catalog toggle from the store page and cleans up unused props/state plumbing, since HomePage is always rendered in catalog mode on the home route.

Main changes:

• HomePage (opennow-stable/src/renderer/src/components/HomePage.tsx):

  • Removed source and onSourceChange props from HomePageProps
  • Removed the toolbar's home-tabs div containing the dead Catalog button

• App (opennow-stable/src/renderer/src/App.tsx):

  • Removed GameSource type and source state variable
  • Simplified loadGames handler to use inline literal union type
  • Updated home-page refresh effect to key off currentPage !== "home" instead of source !== "main"
  • Removed stale setSource calls from catalog browse and reset handlers
  • Removed source and onSourceChange props from HomePage call site

• Styles (opennow-stable/src/renderer/src/styles.css):

  • Removed unused .home-tabs and .home-tab selectors including hover/active/disabled variants

The rest of the toolbar (search, filters, sort, counts, and game grid) remains unchanged.