fix(auth): switch Mastra Studio production domain

[tataihono]

Summary

• switch the production Mastra Studio OAuth client registration to mastra.jesusfilm.org
• update the first-party app seed test for the new canonical domain

Verification

• pnpm --filter @forge/auth test src/domain/apps.test.ts
• pnpm --filter @forge/auth typecheck
• pnpm --filter @forge/auth lint
• pnpm --filter @forge/auth build

Deployment

• gateway MASTRA_GATEWAY_BASE_URL set to https://mastra.jesusfilm.org
• gateway redeployed successfully
• auth deployment started for the OAuth registration code change

[railway-app]

🚅 Deployed to the forge-pr-997 environment in forge

10 services not affected by this PR

• @forge/web
• @forge/admin/redis
• @forge/cms/db
• @forge/admin/db
• @forge/roadmap
• @forge/cms
• @forge/agentic-studio
• @forge/agentic
• @forge/admin
• @forge/manager