Add domain verification guard to schema publication script
Changes:
- Update scripts/publishSchema.ts: Add domain ownership verification
- Add SCHEMA_PUBLISHER_USERNAME and SCHEMA_PUBLISHER_PASSWORD env vars
- Verify logged-in account handle contains expected domain
- Provide clear error messages for template users who accidentally run script
- Update scripts/README.md: Document new credential approach
- Update .env.example: Add schema publisher credential placeholders
This prevents template users from accidentally publishing duplicate schemas
while allowing the voyager.studio domain owner to publish independently
from any Bluesky account with a voyager.studio handle.
The script can now be run with:
SCHEMA_PUBLISHER_USERNAME=handle SCHEMA_PUBLISHER_PASSWORD=pass deno task publish-schema