fix: use publication base_path for correct leaflet urls
- store publication_uri on documents, base_path on publications
- join in search query to return base_path with results
- frontend builds urls as https://{basePath}/{rkey}
- add shareable search urls via ?q= query param
- add source link to tangled repo
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>