Use remote function to ReadNext

The ReadNext component should suggest related articles based on shared tags, excluding the current article.

Current State

Currently reads from page.data.readNextPosts which is not populated. The component needs to self-resolve suggestions from the feed.

Requirements

• Load articles from the feed that share at least one tag with the current article
• Exclude the current article from results
• Sort by number of shared tags (most relevant first)
• Limit to 3-4 suggestions
• Fall back to recent articles if no tag matches found

Tasks

• Resolve current page tags from PageMeta (via buildPagesMap or feed data)
• Filter feed items by shared tags, excluding current URL
• Rank by tag overlap count
• Pass filtered posts to the ReadNext template