Add product sorting by rating and star-range filtering

[GeekTrainer]

Summary

Add the ability to sort and filter products on the products listing page by average review rating.

Context

Currently, products on the /products page are displayed alphabetically with no way for users to sort or filter by rating. Users who want to find highly-rated coffees must scan each card individually. Adding sort and filter controls improves discoverability.

Proposed Solution

• Create a new ProductSort.svelte component with:
  • A sort dropdown (Name / Highest Rated) that reorders product cards client-side
  • A star-range filter (min/max dropdowns) that shows/hides products based on rounded average rating
• Add data-name and data-rating attributes to product cards for client-side DOM manipulation
• Import and render the component in src/pages/products/index.astro

Acceptance Criteria

• Products can be sorted by name (default) or highest rated
• Products can be filtered by a min and max star range (0-5)
• Min/max selects stay consistent (min never exceeds max)
• No page reload required for sort or filter changes

Additional Information

This follows the same client-side DOM manipulation pattern used by the existing ReviewFilter.svelte component.