feat: add merge-pull-request.sh tool for automated PR merging with branch cleanup

[isaaceliape]

Add new tool to automate PR merging with automatic source branch cleanup.

Features

✨ Streamlined PR merge workflow:

• Merge pull requests using multiple strategies (squash, merge, rebase)
• Automatically delete source branch after successful merge
• Support for force merge without confirmation
• Dry-run mode for safe preview
• Status check verification
• Clear error handling and logging

Usage Examples

# Merge PR #35 using squash strategy and delete branch
./merge-pull-request.sh --pr 35

# Merge with rebase strategy
./merge-pull-request.sh -p 36 --strategy rebase

# Merge without deleting source branch
./merge-pull-request.sh --pr 37 --keep-branch

# Preview merge before applying
./merge-pull-request.sh --pr 38 --dry-run

Changes

• ✅ Created tools/merge-pull-request.sh with full functionality
• ✅ Updated tools/README.md with comprehensive documentation
• ✅ Added Workflow 7 example for merge workflows
• ✅ Updated Quick Reference table
• ✅ Added merge strategy options (squash, merge, rebase)