Add 'My Collection Only' filter to card search

[robertclayh]

Summary

Adds a "My Collection Only" toggle button to the card search results page that filters results to show only cards from packs the user has saved in their collection.

• Toggle is only visible to logged-in users
• Filter persists across pagination
• Uses the existing owned_packs data from the user's saved collection settings

Addresses #114 (specifically the "My Collection" search category suggestion)

Changes

• SearchController.php — reads collection query parameter, fetches user's owned packs, passes them through search and pagination
• searchbar.html.twig — adds the toggle checkbox button to the search bar
• CardsData.php — adds optional $ownedPacks parameter to get_search_rows() to filter by pack IDs

Test plan

• Log in and go to /search, search for any cards (e.g. t:hero)
• Verify "My Collection Only" toggle appears next to sort/view options
• Check the toggle and search again — results should only include cards from owned packs
• Verify pagination links preserve the collection filter
• Verify the toggle does not appear when logged out