Publish spec eabae21 and sync Connect schemas to production beta125

[callumalpass]

• The specification moves from bad38995 to mdbase-dev/mdbase-spec@eabae21. This publishes 05A's seed upgrade rules (upgrade_from baseline lists and seed origins, spec Publish TaskNotes pack rc.16 #59) and the invalid-manifest rules (State Reader extension Limited Use commitment #60).
• public/connect/schemas is re-synced from the already pinned Connect ref 5548e106 (beta125, in production). The served copies had not been synced since Align website with production Connect releases #20, so mdbase-app.schema.json did not describe upgrade_from at all. Six schemas published by Connect since then are added. Release automation moves the Connect ref but does not re-sync these files.

Generated with pnpm sync:sources against checkouts at the pinned refs. The engine refs and claim files are unchanged; conformance data differs only in its date. pnpm check and pnpm build pass locally. Spec import and link checks need the spec site build, which CI produces.

[callumalpass]

Correction to the description: the deployed site was not serving stale Connect schemas. deploy.yml and ci.yml run pnpm sync:sources from the pinned refs before every build, so production already served the beta125 schemas once #77 merged. Only the copies committed in git were stale (last synced in #20). The release automation doesn't need to re-sync them for the live site to be correct.