feat: apply template setup values during template workflow creation

[mackeh]

Summary

• apply Template Setup Wizard values when creating workflows from templates
• support setup placeholder rendering in server templates via {{setup.key}} syntax
• add API support for setupValues in POST /api/workflows/from-template
• update integration readiness checks to honor overridden integration names
• add tests for setup rendering and check-id mapping
• update README, API reference, demos, and changelog

Validation

• cd apps/server && npm test
• cd apps/server && npm run test:templates
• cd apps/server && npm run build
• cd apps/web && npm test && npm run build

Notes

• main is branch-protected, so this ships through PR/CI merge flow