Integration tests: assert canonical Job Board functionality in CI

[snissn]

Adds a canonical end-to-end integration test for apps/example/job-board.schema.json and makes it part of the required local integration CI gate.

What this asserts

• Build succeeds for canonical example.
• th preview auto-deploy path produces a non-zero deployment address.
• Canonical UI routes return 200.
• Candidate collection works end-to-end on-chain:
  • create
  • list/get
  • update
  • soft delete + includeDeleted semantics
• JobPosting paid create is enforced:
  • create without payment fails
  • create with required amountWei succeeds
  • update + delete behave correctly

Why

• Protects the canonical app from regressions in generated contract/UI behavior.
• Catches functional breakages in CI before merge instead of at manual QA time.

Validation (local)

• pnpm test:integration
• pnpm test
• pnpm typecheck