Add graph-derived "Related Episodes" and "Related Books" sections to podcast pages

Feedback

"Maybe based on the graph, make related podcasts / related episodes — like the one I have at the very bottom now, except mine just lists the episodes from this same season. It could instead build related episodes based on the graph. And likewise related books."

Current behavior

The bottom of a podcast page currently shows episodes from the same season (a static list), not episodes that are actually related by content/connections. The graph already computes cross-links (podcast ↔ topic ↔ book ↔ person), but that signal isn't reused for a curated "related" list.

Proposed change

Add dedicated sections at the bottom of each podcast page, computed from the graph connections:

• Related Episodes — other podcasts that share the most topics/people with this one (graph-based similarity), replacing or augmenting the same-season list.
• Related Books — books connected through shared topics/guests.

Each item should show enough context (title, maybe guest/thumbnail) to be clickable and inviting — not just a bare link.

Files

• _layouts/podcast_summary.html (currently ends with <section class="graph-connections" data-graph-connections hidden>)
• assets/page-graph.js (graph data + neighbour computation already lives here)

Related

• Depends on the same graph-similarity signal as #7 (related podcasts first).

Source: user feedback (translated from Russian voice note). Perspective: someone browsing a specific podcast episode page.

Start with _layouts/podcast_summary.html and assets/page-graph.js, then inspect the existing graph data and neighbour computation. Compare the related-podcast signal in #7 with the requested episode and book sections. Done means podcast pages render graph-derived Related Episodes and Related Books with clickable items and useful context instead of relying only on the same-season list.