Add Docker services for Rails 7.1-8.1 testing

Expand docker-compose.yml to include services for all supported
Rails versions from the CI matrix:

Services added:
- rails-7.1: Rails 7.1.6
- rails-7.2: Rails 7.2.3
- rails-8.0: Rails 8.0.4
- rails-8.1: Rails 8.1.2

Updated services:
- rails-6.1: 6.1.7 → 6.1.7.10
- rails-7.0: 7.0.4 → 7.0.10
- shell: default Rails version 6.1.7 → 8.1.2

Usage:
  docker-compose run rails-7.1
  docker-compose run rails-7.2
  docker-compose run rails-8.0
  docker-compose run rails-8.1

This matches the expanded CI matrix and enables local testing
across all supported Rails versions.

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

Author: takaokouji

docker-compose.yml

@@ -11,28 +11,60 @@ services:
     stdin_open: true
     tty: true
 
-  # Rails 6.1.7
+  # Rails 6.1.7.10
   rails-6.1:
     <<: *test-base
     container_name: jsonapi-rails-6.1
     environment:
-      - RAILS_VERSION=6.1.7
+      - RAILS_VERSION=6.1.7.10
     command: bash -c "bundle update && bundle exec rake test"
 
-  # Rails 7.0.4
+  # Rails 7.0.10
   rails-7.0:
     <<: *test-base
     container_name: jsonapi-rails-7.0
     environment:
-      - RAILS_VERSION=7.0.4
+      - RAILS_VERSION=7.0.10
     command: bash -c "bundle update && bundle exec rake test"
 
-  # Interactive shell for debugging (defaults to Rails 6.1)
+  # Rails 7.1.6
+  rails-7.1:
+    <<: *test-base
+    container_name: jsonapi-rails-7.1
+    environment:
+      - RAILS_VERSION=7.1.6
+    command: bash -c "bundle update && bundle exec rake test"
+
+  # Rails 7.2.3
+  rails-7.2:
+    <<: *test-base
+    container_name: jsonapi-rails-7.2
+    environment:
+      - RAILS_VERSION=7.2.3
+    command: bash -c "bundle update && bundle exec rake test"
+
+  # Rails 8.0.4
+  rails-8.0:
+    <<: *test-base
+    container_name: jsonapi-rails-8.0
+    environment:
+      - RAILS_VERSION=8.0.4
+    command: bash -c "bundle update && bundle exec rake test"
+
+  # Rails 8.1.2
+  rails-8.1:
+    <<: *test-base
+    container_name: jsonapi-rails-8.1
+    environment:
+      - RAILS_VERSION=8.1.2
+    command: bash -c "bundle update && bundle exec rake test"
+
+  # Interactive shell for debugging (defaults to Rails 8.1)
   shell:
     <<: *test-base
     container_name: jsonapi-shell
     environment:
-      - RAILS_VERSION=${RAILS_VERSION:-6.1.7}
+      - RAILS_VERSION=${RAILS_VERSION:-8.1.2}
     command: /bin/bash
 
 volumes: