fix(discord-gateway): generate Drizzle migrations and copy to Docker image

Container crashed with 'Can't find meta/_journal.json file' because
Drizzle ORM migration files were never generated. Generated migrations
for all 10 schema tables and updated Dockerfile to copy drizzle/ to
/app/drizzle/ where the migrator expects them.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infra/docker/Dockerfile.discord-gateway

@@ -16,6 +16,9 @@ COPY vendor/discord.js-selfbot-v13 ./vendor/discord.js-selfbot-v13
 # Copy service
 COPY services/discord-gateway ./services/discord-gateway
 
+# Copy Drizzle migrations (relative path used by migrator)
+COPY services/discord-gateway/drizzle ./drizzle
+
 # Install dependencies
 RUN pnpm install --frozen-lockfile