M9-S8: seller-obligation e2e + M9 close housekeeping

[erikshafer]

Closes the M9 Seller Console milestone — the slice plan's close (renumbered from S7 to S8 after the CatalogListingView cross-queue race fix took S7 mid-milestone).

What's in this PR

Seller-perspective Playwright e2e (client/e2e/tests/seller-obligation.spec.ts) — the milestone's last owed artifact and the full obligation-lifecycle e2e M9-S6 deferred here. From the seller console's vantage: a seeded listing sells (forced via the dev Buy-It-Now trigger), the console surfaces the post-sale obligation, the seller provides tracking through the react-hook-form dialog, and the obligation auto-confirms to Fulfilled / "Completed". Two consecutive green runs against the live Aspire stack (17.6s, 13.3s).

Sanctioned dev-host config — the AppHost now sets Obligations__DemoMode=true. Reading the lived host config (frontend-slice-discipline Rule 1) surfaced that ObligationsOptions.DemoMode defaulted to false in the dev run, so the post-sale lifecycle ran on production timers (auto-confirm 3 days out) — making it un-demoable live and the e2e terminal unreachable. Enabling demo mode is the documented conference-demo posture; production binds DemoMode=false by default. (Escalated and user-confirmed mid-session, since it exceeded the "no backend change" envelope.)

Identity bridge = seed-then-inject (OQ-1) — the dev seed-flash endpoint already creates a registered seller + open listing; the e2e injects that sellerId into the console's session storage so the console adopts the seeded identity. No backend change; operator session management stays out of the seller console (milestone §3 non-goal).

Housekeeping

• bounded-contexts.md: three SPAs + shared + e2e (was two SPAs).
• STATUS.md: regenerated to v0.7 — M9 ✅ Complete, final slice ledger, 328 backend / 189 Vitest / 2 e2e, deferred ledger re-derived.
• Milestone doc: status ✅ Complete, §7 slice table corrected (S7 = race fix, S8 = close), §1 exit criteria ticked with honest annotations.
• CLAUDE.md §Frontend: verified current (no edit needed).
• CI frontend matrix: verified it already covers seller (build-test) + shared/e2e (typecheck) — coverage landed at M9-S1, restructured at fix: remove shouldUnregister bug + CI pipeline restructure #111. No matrix edit.

Pre-M10 skills audit (per the m9-skills-review carry-forward)

• Applied in-PR: frontend-slice-discipline extended to all SPAs + the e2e harness, and a Rule 1 note that host runtime config is part of the lived surface (the DemoMode lesson).
• Carry-forwards to M10: a signalr-skill refresh (seller + the createSignalRProvider factory + the obligation push channel), the FakeHubConnection shared test-util extraction.

Retros: the M9-S8 slice retro + the M9 milestone retrospective.

Verification

• dotnet build clean (0 errors; held NU1903 + CS0108 baseline warnings only).
• dotnet test CritterBids.slnx: 328/328 green (Auctions 77, Api 46, Selling 45, Relay 45, Operations 38, Settlement 30, Listings 24, Obligations 16, Participants 6, Contracts 1).
• SPA Vitest: bidder 25, ops 47, seller 117 (189) green; @critterbids/e2e type-checks clean.
• Seller e2e: two consecutive green runs against the live Aspire stack.

Notes for review

• Only domain-adjacent .cs change is one line in src/CritterBids.AppHost/Program.cs (the DemoMode dev-host env var). No CritterBids.Contracts change, no new domain events/sagas/BCs.
• The e2e is local-only by recorded decision (M8-D2); the e2e member is type-checked in CI, not executed.