chore(docker): include backfill script in image

Backfill must read the SQLite volume that lives inside the api/jetstream
containers, so it has to be runnable via `deno task backfill:search`
from a Coolify exec shell.

.dockerignore

@@ -19,6 +19,9 @@ remote-db/
 
 # admin / dev-only scripts (run locally, not in prod containers)
 scripts/
+# Backfill needs to run inside the api/jetstream container so it can read
+# the shared SQLite volume; ship it in the image.
+!scripts/backfill-opensearch.ts
 
 # logs and caches
 *.log