Add Saffron Phase 1 runtime smoke checklist #52

Before Saffron stops grooming GitHub Projects and starts using Mission Control as her task visibility layer, we need a clear runtime smoke checklist.

Acceptance criteria — Document checks for:

• GET /api/health returns healthy (ok: true, database: ok)
• POST /api/automation/sync succeeds
• GET /api/automation/repos returns repos
• POST /api/sync returns syncedCount > 0
• GET /api/issues returns issues
• Board shows issues
• Projects shows repo groups
• Saffron heartbeat appears in Agents
• Moving one low-risk test issue updates GitHub labels and writes AuditLog
• Logs show no Prisma, BigInt, or FK errors
• Mission Control failures do not break Saffron heartbeat

This should be documented as a runnable checklist (e.g., a script, markdown doc, or CI step) that can be executed before cutover.