feat: add Counterparty Evidence Desk fixture service

[mj-deving]

Summary

Adds a first runnable Directory service slice: Counterparty Evidence Desk.

This is intentionally fixture-backed and no-spend. It gives the Directory a visible service card, service detail page, runnable UI, machine contract JSON, and verifier-backed receipt flow without claiming live source truth, live payment, settlement, certification, or chain anchoring.

What changed

• adds a Counterparty Evidence Desk seller/listing fixture
• adds a CounterpartyEvidenceReceipt fixture and verifier checks
• adds /api/dacs/counterparty-evidence/run for the no-spend fixture run
• adds a service-page runner component
• preserves fixture seeds through reindex without making generic chain reads accept fixture: locators
• labels the listing as fixture-only / not chain anchored in human-facing surfaces
• adds regression coverage for receipt integrity, tamper negatives, fixture seeding, listing JSON, and the generic-chain-reader trust boundary

Trust boundary

The receipt proves fixture receipt integrity and authorship only. It does not prove source truth, compliance clearance, sanctions clearance, payment readiness, settlement, or chain inclusion. The UI also reports the fixture freshness state explicitly.

Validation

• git merge-tree origin/main HEAD clean
• git diff --check
• bun run test - 41/41 pass
• bun run typecheck
• bun run build
• browser QA on local service page, desktop and mobile: no console errors, no horizontal overflow, runner visible
• fixture run API returned a verification report with 10 checks
• autoreview --mode branch --base origin/main clean after fixing the accepted fixture/chain-reader boundary finding

Notes

bun run index was not used as a pass/fail gate here: without live deployment config it enters the chain-scan path and timed out locally. The fixture seed path and mocked reindex preservation are covered by tests.