Implements end-to-end automation for detecting new Ruby versions from
rbenv/ruby-build and publishing features/images with approval gates.

Key Features:
- Daily check for new Ruby versions (>= 3.2.0 non-EOL only)
- Automatic PR creation with auto-merge on CI success
- Conditional publishing: full rebuild on feature bump, incremental otherwise
- Single approval gate for all publishing operations
- Comprehensive workflow annotations and failure notifications

Workflows:
- check-ruby-versions.yaml: Daily cron + manual trigger for detection
- publish-ruby-updates.yaml: Handles feature/image publishing with approval
- Modified release-features.yaml: Excludes Ruby feature from batch publish
- Modified publish-new-image-version.yaml: Uses dynamic matrix from JSON

Scripts:
- find-new-ruby-versions: Fetches and filters versions from ruby-build
- check-and-create-pr: Orchestrates detection and PR creation
- create-ruby-versions-pr: Creates formatted PR with automation labels
- check-feature-bump: Detects feature version changes in commits
- extract-new-ruby-versions: Parses new versions from git diff
- get-current-image-version: Gets latest ruby-* tag
- Modified add-ruby-version: Uses JSON storage instead of YAML

Infrastructure:
- .github/ruby-versions.json: Single source of truth for version matrix
- Uses RUBY_AUTOMATION_PAT for proper workflow triggering
- Proper stdout/stderr separation for script composition
- yq installed in devcontainer for JSON/YAML manipulation

Workflow Behavior:
- Feature bump: Publish feature → create release → tag → build all versions
- No bump: Trigger builds for new Ruby versions only
- Approval step shows summary of what will be published
- Failure notifications create GitHub issues automatically