Add sync-d1 workflow: issue edits reconcile the catalog into D1

api/README.md

@@ -59,6 +59,10 @@ routes). Bindings in `wrangler.jsonc`: `DB` (D1 `srs`), `EMAIL`
 (`send_email`, restricted to the verified destination). Sender domain
 `prdlk.com` is onboarded to Email Sending.
 
+The `sync-d1.yml` Actions workflow additionally pushes curriculum issue
+edits into D1 immediately (`POST /admin/reconcile` with the
+`SRS_ADMIN_KEY` repo secret); the morning cron is the backstop.
+
 ## Local dev
 
 ```sh