Enhance blog and events pages with pagination, filtering, and responsive images #42
Description
Polish the blog and events listing pages to handle the content we'll be migrating. We need:
- Pagination: 12 posts per page for blog, 15 per page for events
- Year filtering: Add dropdown/buttons to filter blog posts by year (replace the "Year filtering will be added later" placeholder in
templates/core/blog_index.html:14-16) - Responsive images: Switch from {% image page.header_image original %} to Wagtail's rendition system (e.g., fill-400x250 format-webp) for
better performance. Update all templates that display images (blog_index, events_index, home.html, blog_page, event_page)