Migrate Danger to use danger-pr-comment workflow.

- Migrated from custom Danger setup to danger-pr-comment workflow framework
- Replaced manual Danger workflow with reusable workflows from numbata/danger-pr-comment
- Added .github/workflows/danger.yml using danger-pr-comment reusable workflow
- Added .github/workflows/danger-comment.yml for posting PR comments
- Updated Gemfile to include danger, danger-pr-comment, danger-changelog, and danger-toc
- Updated Dangerfile to import danger-pr-comment and added changelog.check! and toc.check!

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: dblock

.github/workflows/danger-comment.yml

@@ -0,0 +1,11 @@
+name: Danger Comment
+
+on:
+  workflow_run:
+    workflows: [Danger]
+    types: [completed]
+
+jobs:
+  comment:
+    uses: numbata/danger-pr-comment/.github/workflows/danger-comment.yml@v0.1.0
+    secrets: inherit

.github/workflows/danger.yml

@@ -1,21 +1,13 @@
----
-name: danger
-on: pull_request
+name: Danger
+
+on:
+  pull_request:
+    types: [opened, reopened, edited, synchronize]
 
 jobs:
   danger:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v4
-      with:
-        fetch-depth: 100    
-    - name: Set up Ruby
-      uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: 3.4
-        bundler-cache: true
-    - name: Run Danger
-      run: |
-        # the token is public, has public_repo scope and belongs to the grape-bot user owned by @dblock, this is ok
-        TOKEN=$(echo -n Z2hwX2lYb0dPNXNyejYzOFJyaTV3QUxUdkNiS1dtblFwZTFuRXpmMwo= | base64 --decode)
-        DANGER_GITHUB_API_TOKEN=$TOKEN bundle exec danger --verbose
+    uses: numbata/danger-pr-comment/.github/workflows/danger-run.yml@v0.1.0
+    secrets: inherit
+    with:
+      ruby-version: '3.4'
+      bundler-cache: true

Dangerfile

@@ -1,3 +1,7 @@
 # frozen_string_literal: true
 
+danger.import_dangerfile(gem: 'danger-pr-comment')
 danger.import_dangerfile(gem: 'ruby-grape-danger')
+
+changelog.check!
+toc.check!

Gemfile

@@ -23,6 +23,10 @@ group :development do
 end
 
 group :test do
+  gem 'danger', require: false
+  gem 'danger-changelog', require: false
+  gem 'danger-pr-comment', require: false
+  gem 'danger-toc', require: false
   gem 'rack-contrib', require: false
   gem 'rack-test', '~> 2.1'
   gem 'rspec', '~> 3.13'