feat: add branch exclusion feature with regex patterns

Users can now exclude branches from synchronization using regex patterns
in the configuration file. This is useful for:
- Excluding temporary or experimental branches
- Skipping vendor or third-party branches
- Ignoring deployment-specific branches

Configuration example:
```json
{
  "exclude_branches": [
    "^codex/",    // Exclude branches starting with "codex/"
    "^temp-",     // Exclude branches starting with "temp-"
    "-wip$"       // Exclude branches ending with "-wip"
  ]
}
```

Features:
- Regex pattern matching for flexible exclusion rules
- Clear reporting of excluded branches during sync
- Excluded branches are filtered from sync but still analyzed for abandonment
- Invalid regex patterns are reported but don't stop sync

The feature helps maintain cleaner synchronization by allowing users to
ignore branches that shouldn't be synchronized across all repositories.

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

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

1 files changed, 20 insertions, 1 deletions

diff --git a/internal/sync/sync.go b/internal/sync/sync.go
index 4d46ca8..b413318 100644
--- a/internal/sync/sync.go
+++ b/internal/sync/sync.go
@@ -16,15 +16,25 @@ type Syncer struct {
 	workDir  string
 	repoName string
 	abandonedReports map[string]*AbandonedBranchReport // Collects reports across repos
+	branchFilter     *BranchFilter                     // Filter for excluding branches
 }
 
 // CLAUDE: Is there a reason, we return a pointer to Syncer?
 // New creates a new Syncer instance
 func New(cfg *config.Config, workDir string) *Syncer {
+	// Create branch filter
+	branchFilter, err := NewBranchFilter(cfg.ExcludeBranches)
+	if err != nil {
+		// Log error but continue without filter
+		fmt.Printf("Warning: Failed to create branch filter: %v\n", err)
+		branchFilter = &BranchFilter{}
+	}
+
 	return &Syncer{
 		config:  cfg,
 		workDir: workDir,
 		abandonedReports: make(map[string]*AbandonedBranchReport),
+		branchFilter:     branchFilter,
 	}
 }
 
@@ -57,11 +67,20 @@ func (s *Syncer) SyncRepository(repoName string) error {
 	}
 
 	// Get all branches
-	branches, err := s.getAllBranches()
+	allBranches, err := s.getAllBranches()
 	if err != nil {
 		return fmt.Errorf("failed to get branches: %w", err)
 	}
 
+	// Filter branches based on exclusion patterns
+	branches := s.branchFilter.FilterBranches(allBranches)
+	excludedBranches := s.branchFilter.GetExcludedBranches(allBranches)
+	
+	// Report excluded branches if any
+	if exclusionReport := FormatExclusionReport(excludedBranches, s.config.ExcludeBranches); exclusionReport != "" {
+		fmt.Print(exclusionReport)
+	}
+
 	// Get remotes map
 	remotes := s.getRemotesMap()