feat: add real-world starter template pack + docs

[mackeh]

Summary

• add five production-style workflow templates to the built-in template catalog
• expand template tests to assert new template coverage and metadata
• update README, demos, API reference, docs index, and changelog for discoverability

Templates Added

• invoice-intake-approval
• web-scrape-api-sync
• csv-cleanup-validation
• email-triage-ticket-create
• scheduled-health-check-alert

Validation

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

Notes

• this change is additive and does not alter existing template IDs
• docs were updated to keep onboarding and demos aligned with shipped capabilities