fix(db): correct migration 0012 timestamp — drizzle skips when < last applied

Drizzle 0.45 migrate() runs only migrations with folderMillis > the
latest created_at in __drizzle_migrations. Hand-written when was
1781580000000 (June 16) < stored 1781672400000 (June 17), so 0012 was
silently skipped and the embedding column never created. Bumped when to
now; migrator will apply it on next deploy.

services/discord-gateway/drizzle/migrations/meta/_journal.json

@@ -89,7 +89,7 @@
     {
       "idx": 12,
       "version": "7",
-      "when": 1781580000000,
+      "when": 1785500000000,
       "tag": "0012_add_embedding_to_text_cache",
       "breakpoints": true
     }