fix(db): index the keyword projection by document for the ACL fan-out trigger

The document ACL trigger updates the keyword projection by document id; the projection had no index on that column, so every document ACL or source change scanned the whole projection. Adds the index concurrently.

Author: waleedlatif1

packages/db/migrations/0373_keyword_tin_document_index.sql

@@ -0,0 +1,6 @@
+-- The document ACL trigger fans a document's source and ACL out to the keyword projection by
+-- document id; with no index on that column every ACL change scanned the whole projection.
+COMMIT;--> statement-breakpoint
+SET lock_timeout = 0;--> statement-breakpoint
+CREATE INDEX CONCURRENTLY IF NOT EXISTS "embedding_keyword_tin_document_idx" ON "embedding_keyword_tin" USING btree ("document_id");--> statement-breakpoint
+SET lock_timeout = '5s';