Entity chips for wiki pages (topics, people, books, podcasts+timestamp)

[alexeygrigorev]

Render inline references in wiki prose as typed entity chips (colour + icon per type, matching the graph legend).

• Types: wiki/topic (green), person (purple), book (blue), podcast (amber).
• Podcast chips include the timestamp when present (e.g. Product Analytics and A/B Testing · 27:52).
• Implemented as an extension: assets/entity-chips.js (client-side enhancer over entity links) + assets/pagecss/chips.css. DONE.
• Follow-up: fan out subagents to convert the markdown so entity mentions are linked (and thus chipped) and podcast refs carry timestamps. Conservative, per-file.
• Future option: a build-time rustkyll extension / shortcode instead of client-side JS.