feat(example): Package & Issuance browser in web_ui_demo — campus tree + issue-revision + compare drill-ins

[thewrz]

Why

The demo has zero package/revision client code: no api.js functions for the existing routes, no view renders packages or issuances, no API_FEATURES flag — even though server.mjs already proxies /packages and /revisions, and the MCP chat already lists list_packages / issue_package_revision / get_revision. The campus story (Client → Project → Package → Issuance → CCD, packages as overlapping lenses like Campus Underground vs Building A Core & Shell, per-package non-linear issuance clocks) is invisible in the demo.

What (all inside examples/web_ui_demo/ — example/POC code, no src/ changes)

1. Packages view tab (pattern-match existing tabs): list the active project's packages with ordered member specs (GET /projects/{id}/packages); create a package; edit membership (PUT /packages/{id}/specs, reusing the board's project-member specs).
2. Issuance timeline per package (needs feat(api): list a package's revisions — GET /packages/{id}/revisions #388): ordered revision list with type/phase/number/date badges rendered from the nomenclature profile (GET /projects/{id}/revision-nomenclature); "Issue revision" form driven by the profile's type fields (structured create body); nest children under parentRevisionId and show baseRevisionId lineage when present (feat(db/api): issuance nesting — parent_revision_id on package_revisions (CCDs under issuances, ADR required) #389/feat(db/api): persist addendum comparison base — base_revision_id on package_revisions #390 — feature-detect).
3. Compare drill-ins: select two issuances (or live package vs issuance) → hand off to the Compare view / compare_specs-per-section or compare_scopes when available (feat(reporting): frozen revision trees as comparison sources — polymorphic compare refs + freeze-time origin embedding (ADR required) #392/feat(reporting): scope rollup comparison — project↔project, package↔package, issuance↔issuance over shared sections #393 — feature-detect; degrade to today's live-spec Compare).
4. Plumbing: api.js functions for the package/revision routes; one API_FEATURES.packages flag gating the tab; README walkthrough — a scripted campus scenario (multi-building project, an underground-only package, a permit issuance, an addendum, a CCD under a bulletin).

OpenAPI ↔ MCP contract lockstep

No API change: consumes existing + this series' contracts read/write from example code only. If implementation reveals a needed contract change, STOP and file it separately with the lockstep blurb — never drift the demo from the spec.

Prior art / cross-links

• PR feat(example): Compare view in web_ui_demo — side-by-side grounded matrix + Ask-SpecR summarize handoff #386 (Compare view + handoff patterns), PR feat(example): agent-driven grounded reporting in web_ui_demo — Compose cited reports over MCP #361 (Compose), feat(examples): surface recently-landed backend capabilities in the web demo #280/feat(examples): coordination audit view + numbering workspace + MCP chat + light re-theme #324 (demo build-outs); not the Phase-5 product UI (feat(ui): Phase 5a — frontend scaffold (React/TS, Vite, openapi-fetch client) #38–feat(ui): Phase 5e — firm library management #42) — this is the POC surface.
• Revision DOCX egress stays REST-only (POST /revisions/{id}/generate is MCP_UNEXPOSED) — the browser calls it through the proxy, agents don't.

Non-goals

• Building any backend behavior; auth/persistence; PDF (feat(generator): PDF artifact egress — render specs to PDF sharing the DOCX style + CSI numbering source-of-truth #352).

Acceptance

• With feat(api): list a package's revisions — GET /packages/{id}/revisions #388 live: the tab lists packages + issuance timelines; issuing a revision from the form appears in the timeline; nesting/base render when the backend supports them; compare drill-in lands in the Compare view with the right sources; demo suites stay green (node --test examples/web_ui_demo/*.test.mjs) with new pure helpers covered; README campus walkthrough reproduces end-to-end.

Hard dependency: #388. Feature-detects #389/#390/#392/#393.