ci: add 'merge' as valid commit type in PR validation

- Updated PR validation workflow to accept 'merge:' commit type
- Added 'merge' to allowed types in both title and commit validation
- Updated CONTRIBUTING.md to document merge commit type
- Enables proper validation of branch synchronization commits

This allows merge commits like 'merge: sync branch with latest changes'
to pass validation without errors.

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

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

Author: Agent Communication MCP Server

.github/workflows/pr-validation.yml

@@ -35,14 +35,14 @@ jobs:
           # Check conventional commit format (skip emoji stripping for now)
           CLEANED_TITLE="$PR_TITLE"
           
-          if echo "$CLEANED_TITLE" | grep -qE '^(feat|fix|docs|style|refactor|perf|test|chore|ci|build|resolve)(\([^)]+\))?(!)?: .+'; then
+          if echo "$CLEANED_TITLE" | grep -qE '^(feat|fix|docs|style|refactor|perf|test|chore|ci|build|resolve|merge)(\([^)]+\))?(!)?: .+'; then
             echo "✅ PR title follows conventional commit format"
             echo "valid_title=true" >> $GITHUB_OUTPUT
-            
+
             # Extract type for labeling from cleaned title
             TYPE=$(echo "$CLEANED_TITLE" | sed -E 's/^([a-z]+)(\([^)]+\))?(!)?: .*/\1/')
             echo "pr_type=$TYPE" >> $GITHUB_OUTPUT
-            
+
             # Check for breaking change indicator
             if echo "$PR_TITLE" | grep -q '!:'; then
               echo "breaking_change=true" >> $GITHUB_OUTPUT
@@ -52,7 +52,7 @@ jobs:
           else
             echo "❌ PR title does not follow conventional commit format"
             echo "Expected format: type(scope): description"
-            echo "Valid types: feat, fix, docs, style, refactor, perf, test, chore, ci, build, resolve"
+            echo "Valid types: feat, fix, docs, style, refactor, perf, test, chore, ci, build, resolve, merge"
             echo "valid_title=false" >> $GITHUB_OUTPUT
           fi
           
@@ -76,7 +76,7 @@ jobs:
             if echo "$commit_msg" | grep -qE '^Merge (branch|pull request)'; then
               echo "  ⏭️ Skipping merge commit"
               VALID_COUNT=$((VALID_COUNT + 1))
-            elif echo "$commit_msg" | grep -qE '^(feat|fix|docs|style|refactor|perf|test|chore|ci|build|resolve)(\([^)]+\))?(!)?: .+'; then
+            elif echo "$commit_msg" | grep -qE '^(feat|fix|docs|style|refactor|perf|test|chore|ci|build|resolve|merge)(\([^)]+\))?(!)?: .+'; then
               VALID_COUNT=$((VALID_COUNT + 1))
               echo "  ✅ Valid"
             else
@@ -147,7 +147,7 @@ jobs:
           
           **Expected format:** `type(scope): description`
           
-          **Valid types:** feat, fix, docs, style, refactor, perf, test, chore, ci, build, resolve
+          **Valid types:** feat, fix, docs, style, refactor, perf, test, chore, ci, build, resolve, merge
           
           **Examples:**
           - `feat: add new MCP tool for task delegation`

CONTRIBUTING.md

@@ -52,7 +52,7 @@ type(scope): description
 
 #### Commit Types
 - **feat**: New features (triggers minor version bump)
-- **fix**: Bug fixes (triggers patch version bump) 
+- **fix**: Bug fixes (triggers patch version bump)
 - **docs**: Documentation changes only
 - **style**: Code style changes (formatting, no logic changes)
 - **refactor**: Code restructuring without functionality changes
@@ -61,6 +61,7 @@ type(scope): description
 - **chore**: Maintenance tasks, tooling, dependencies
 - **ci**: CI/CD configuration changes
 - **build**: Build system changes
+- **merge**: Merge commits from branch synchronization
 
 #### Breaking Changes
 For breaking changes, add `!` after type or include `BREAKING CHANGE:` in footer:
@@ -141,6 +142,7 @@ We follow [Conventional Commits](https://conventionalcommits.org/) with semantic
 - `chore`: Maintenance tasks (deps, build, etc.)
 - `perf`: Performance improvements
 - `ci`: CI/CD pipeline changes
+- `merge`: Branch merge commits
 
 ### Examples
 ```bash