ci: switch to Selectel CR for Docker images

Replace Docker Hub postgres with Selectel Container Registry to avoid
rate limits.

Changed:
- postgres → cr.selcloud.ru/brandymint/dockerhub/library/postgres:17
- Added credentials for Selectel CR

Requires: SELCLOUD_TOKEN secret in GitHub repository settings.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dapi

.github/workflows/ci.yml

@@ -42,7 +42,10 @@ jobs:
 
     services:
       postgres:
-        image: postgres
+        image: cr.selcloud.ru/brandymint/dockerhub/library/postgres:17
+        credentials:
+          username: token
+          password: ${{ secrets.SELCLOUD_TOKEN }}
         env:
           POSTGRES_USER: postgres
           POSTGRES_PASSWORD: postgres
@@ -51,7 +54,10 @@ jobs:
         options: --health-cmd="pg_isready" --health-interval=10s --health-timeout=5s --health-retries=3
 
       # redis:
-      #   image: redis
+      #   image: cr.selcloud.ru/brandymint/dockerhub/library/redis:latest
+      #   credentials:
+      #     username: token
+      #     password: ${{ secrets.SELCLOUD_TOKEN }}
       #   ports:
       #     - 6379:6379
       #   options: --health-cmd "redis-cli ping" --health-interval 10s --health-timeout 5s --health-retries 5