Mine the one research dir not yet promoted (260608-wikiengines-overview) into
the catalog. Adds four heterogeneous-backend attachment scenarios the other
research didn't surface:
- UC-34 attach structured/semantic shard without lossy flattening (SMW, XWiki)
- UC-35 attach shard with coarse write granularity (TiddlyWiki single-file)
- UC-36 supply git-addressable history to internal-history engine (Confluence)
- UC-37 attach static export as read-only backup shard (MediaWiki dump)
Adds a `wikiengines` source token + traceability column and a wikiengines
mapping subsection. The scan mostly reinforced existing UCs and the L0→L4
ladder; its main yield is adapter-contract constraints tracked in SHARD-WP-0002.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
