feat: add persistent chat agent and indexed batch workflows

compose.yaml

@@ -26,6 +26,9 @@ services:
       test: [CMD-SHELL, "pg_isready -U wisegrade_test -d wisegrade_tests"]
       interval: 5s
       retries: 12
+  test-redis:
+    profiles: [test]
+    image: redis:7-alpine
   test:
     profiles: [test]
     build:
@@ -36,6 +39,7 @@ services:
     environment:
       DATABASE_URL: postgresql+psycopg://wisegrade_test:wisegrade_test@test-db:5432/wisegrade_tests
       TEST_DATABASE_URL: postgresql+psycopg://wisegrade_test:wisegrade_test@test-db:5432/wisegrade_tests
+      REDIS_URL: redis://test-redis:6379/0
       EMBEDDING_MODEL_PATH: /models/bge-m3
       OCR_MODEL_DIR: /models/ocr
     volumes:
@@ -44,6 +48,7 @@ services:
       - ./models:/models:ro
     depends_on:
       test-db: {condition: service_healthy}
+      test-redis: {condition: service_started}
     command: ["pytest", "-q"]
   api:
     build: ./backend