- Create SeedDataService in Infrastructure/Seed with idempotent seeding
- Seed 2 clubs: Sunrise Tennis Club, Valley Cycling Club
- Seed 7 member records (5 unique Keycloak test users)
- Seed 8 work items covering all status states
- Seed 5 shifts with date variety (past, today, future)
- Seed shift signups for realistic partial capacity
- Register SeedDataService in Program.cs with development-only guard
- Use deterministic GUID generation from club names
- Ensure all tenant IDs match for RLS compliance
- Track in learnings.md and evidence files for Task 22 QA
