fix: run migrations from build stage (has pnpm)

Runner stage is minimal — no pnpm. Add migrator service using
build target which has full node_modules + pnpm.

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

deploy.sh

@@ -255,8 +255,8 @@ start_containers() {
 run_migrations() {
   header "Phase 5 — Database migrations"
 
-  log "Running Payload CMS migrations..."
-  docker compose -f "$COMPOSE_FILE" --env-file "$ENV_FILE" exec -T app pnpm payload migrate
+  log "Running Payload CMS migrations (via build stage — has pnpm + full node_modules)..."
+  docker compose -f "$COMPOSE_FILE" --env-file "$ENV_FILE" --profile migrate run --rm migrator
   log "Migrations complete."
 }
 

docker-compose.prod.yml

@@ -12,6 +12,19 @@ services:
       db:
         condition: service_healthy
 
+  migrator:
+    build:
+      context: .
+      target: build
+    command: pnpm payload migrate
+    env_file:
+      - .env.production
+    depends_on:
+      db:
+        condition: service_healthy
+    profiles:
+      - migrate
+
   db:
     image: postgres:17-alpine
     restart: always