ClipBrain v0.2.4 — retrieval-quality polish

Two retrieval-quality polish fixes from fresh-user dogfooding. Context-pack snippets now always show meaningful text instead of occasionally surfacing a bare section heading (like ## Highlights). And a page's connections no longer list the page itself — "Related" links drop self-references, so you only see genuine connections to other captures.

Upgrade: git pull, then restart the ClipBrain server.