Rename public name to "UN/CEFACT Web Vocabulary" (short: Vocab) - and add chat/mail/dmr

Summary

Renames the vocabulary's public-facing name to UN/CEFACT Web Vocabulary (short form Vocab), reorganises the documentation site's information architecture, adds two landing-page community links and a per-item Data Maintenance Request workflow, and fixes the JSON-LD human link on the deployed vocabulary. Five commits, rebased cleanly on main (includes MR !19 (merged)).

Rename: UN/CEFACT Web Vocabulary (short: Vocab)

Applies a deterministic naming rule across both published sites: the expansion "UN Supply Chain Reference Ontology" becomes "UN/CEFACT Web Vocabulary", and the bare acronym "UNSCRO" becomes "Vocab" (or "the Vocab" inline). This covers all authored site pages, the ontology domain labels and headings, the in-band governance marker (now "Proposed Vocab addition"), the diagram narratives and SVGs, the external-vocabulary register, and the page generators. "UNSCRO" is deliberately retained as an internal codename only, in filenames (for example UNSCRO-migration-ledger.csv), ledger data tokens (the migration-ledger reconciler keys on source_vocab == "UNSCRO"), and code identifiers. The unece: namespace is unchanged. A naming note in CLAUDE.md records this split so the codename and the public name stay separate going forward.

Documentation IA: merge the Mappings page away

The Normative Mappings page overlapped both of its neighbours, so it is split and removed. The external-vocabulary content (fidelity tiers, the mapping-targets table, and where the mappings live) moves into the generated External Vocabularies page. The auditable-trail content (sources, the defensible fork, traceability, and validation) moves into Governance, consolidating the former "Defensibility: the ledgers" section and correcting a stale claim that terms carry in-band dcterms:source to BSP. Navigation, the home cards, and every /docs/mappings link are updated to point at the new homes; no dangling references remain.

Landing page: Chat Channel and Mailing List

Adds two call-to-action buttons under the hero tagline, mirroring the UNTP landing page (spec-untp !788). Chat Channel points at the org-level UN/CEFACT Slack invite (shared with UNTP); Mailing List points at the vocabulary's own list, https://gaggle.email/join/web-vocab@gaggle.email. Styled white-on-blue to match the hero, inverting to outlined-white on hover.

Data Maintenance Request link on every item page

Every resolvable item page (class, property, code scheme, concept, collection, and domain) now ends with a link that opens a pre-filled GitLab new-issue form on this repository, using GitLab's issue[title] and issue[description] parameters. The issue arrives titled "DMR for <item>" with a body that links back to the published item and a "Proposed Change" heading. The link text notes that a UNICC GitLab account is required.

Fix: JSON-LD human link on the deployed vocabulary

The human "JSON-LD" link on each vocabulary page pointed at an object that S3 serves as application/ld+json, so browsers rendered it in their JSON tree viewer instead of as raw text (the local server already downgrades that one browser case to text/plain). Adds the missing CloudFront viewer-response function (deploy/cloudfront/jsonld-viewer-response.js, with attach and verify steps in the accompanying README) that rewrites the response Content-Type to text/plain only for browser navigations, leaving machine content negotiation untouched. The future R2

• Worker hosting carries the same rule inline.

Verification

All eight validate-vocab.py gates pass; the documentation site and the resolvable vocabulary both rebuild cleanly; no stray "UNSCRO" remains in any user-facing generated output; and the branch is rebased on the post-!19 main with the origin-country-on-ConsignmentItem change flowing correctly through the regenerated diagrams and property tables.