Validate ProductUsageEvent against analytics catalog

[jjoonleo]

Summary

• Add an in-code first-release Product Usage Event catalog with typed workflow/result/parameter definitions.
• Route schedule_created through ProductUsageEvent.scheduleCreated and reject unknown events, non-allowlisted parameters, forbidden fields, and nested map values before analytics service logging.
• Add catalog tests that compare the in-code catalog to docs/Analytics-Event-Catalog.md and preserve disabled collection behavior.

Closes #548

Tests

• dart run build_runner build --delete-conflicting-outputs
• flutter analyze
• flutter test