Add restart: unless-stopped to all services

Containers had no restart policy, so they didn't auto-start after a Docker
daemon restart or host reboot. unless-stopped restarts on boot and crashes
but respects manual stops.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -2,6 +2,7 @@ services:
   db:
     image: postgres:17-alpine
     container_name: purrse-db
+    restart: unless-stopped
     environment:
       POSTGRES_DB: purrse
       POSTGRES_USER: purrse
@@ -21,6 +22,7 @@ services:
       context: .
       dockerfile: src/Purrse.Api/Dockerfile
     container_name: purrse-api
+    restart: unless-stopped
     environment:
       - ASPNETCORE_ENVIRONMENT=${ASPNETCORE_ENVIRONMENT:-Development}
       - ConnectionStrings__DefaultConnection=Host=db;Port=5432;Database=purrse;Username=purrse;Password=${DB_PASSWORD:-purrse_dev};Ssl Mode=Prefer;Trust Server Certificate=true
@@ -45,6 +47,7 @@ services:
       context: ./frontend
       dockerfile: Dockerfile
     container_name: purrse-frontend
+    restart: unless-stopped
     ports:
       - "9080:80"
     depends_on: