This PR implements enhanced concurrency policies for GitHub Actions workflows that include issue numbers or pull request numbers in their concurrency groups for better workflow isolation and resource management.

Problem

Previously, workflows triggered by issue or pull request events used generic concurrency groups that could cause unnecessary blocking between unrelated issues/PRs:

# Before: All issue workflows share the same concurrency group
concurrency:
  group: "gh-aw-${{ github.workflow }}"

Solution

The new implementation generates context-aware concurrency groups that include relevant issue/PR numbers:

# Issue workflows now include issue number
concurrency:
  group: "gh-aw-${{ github.workflow }}-${{ github.event.issue.number }}"

# PR workflows include PR number with cancellation
concurrency:
  group: "gh-aw-${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}"
  cancel-in-progress: true

# Mixed workflows handle both contexts
concurrency:
  group: "gh-aw-${{ github.workflow }}-${{ github.event.issue.number || github.event.pull_request.number }}"
  cancel-in-progress: true

Key Changes

• Modular Architecture: Refactored concurrency generation with buildConcurrencyGroupKeys() for extensible key building
• Smart Trigger Detection: Added isIssueWorkflow() and isDiscussionWorkflow() helper functions
• Context-Aware Policies: Different concurrency strategies based on workflow trigger types
• Extended Support: Added discussion workflow support as an additional trigger benefit
• Comprehensive Testing: Full test coverage for all new functions and workflow types
• Documentation: Added comprehensive concurrency policies table to frontmatter documentation

Workflow Types Supported

This ensures that workflows operating on different issues/PRs can run concurrently while preventing conflicts within the same context.

Fixes #113.

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