feat: SDLC database separation for CI/testing (#35)

## Summary
- Fix `isProductionDatabase()` to allow CI database (`euchre_camp_ci`)
- Add database schema reset before CI test runs
- Create `global.teardown.ts` for cleanup (CI: full reset, dev/prod: selective cleanup)
- Add `acceptance-tests` job to PR workflow with CI database
- Create `sync-prod-to-dev.js` script for one-way prod→dev sync
- Add `just` recipes: `sync-dev`, `test-prod`, `reset-ci-db`
- Store credentials in `.credentials` (gitignored) with unique CI user

## Testing
Verified against CI database:
- Schema reset works
- Migrations apply correctly
- Test users created successfully
- 219 tests pass (slow but working)

## Next Steps
- Set `CI_DATABASE_URL` as Gitea repository variable

Reviewed-on: #35
Co-authored-by: David Gwilliam <dhgwilliam@gmail.com>
Co-committed-by: David Gwilliam <dhgwilliam@gmail.com>

.gitignore

@@ -15,6 +15,8 @@
 /playwright/.auth/
 /test-results
 /cookies.txt
+.env.test
+prisma/ci.db
 
 # next.js
 /.next/
@@ -59,3 +61,4 @@ playwright-report/
 
 cucumber-pretty
 .env.production
+.credentials