feat(phase-15): add Test Catalog page, template instantiation, and auto-migration entrypoint (T-119, T-120, T-121)

T-119: TestCatalogPage with search, filters (source/platform/severity), template cards grid, and pagination

T-120: TestFromTemplateForm modal with pre-filled fields from template, required field validation, and redirect on creation

T-121: Integrate Available Test Templates section in TechniqueDetailPage with Run This Test buttons; fix missing testStateBadgeColors for new states

Also: add backend entrypoint.sh for automatic Alembic migrations + seed on container startup, add curl to Dockerfile for healthcheck

docker-compose.yml

@@ -84,7 +84,7 @@ services:
         condition: service_started
     volumes:
       - ./backend:/app
-    command: uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload
+    command: sh /app/entrypoint.sh
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
       interval: 10s