fix(merge): add QualityScore field to merge Issue struct

Add QualityScore *float32 field to internal/merge/merge.go to match
internal/types/types.go. Also add last-touched to .beads/.gitignore.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.beads/.gitignore

@@ -11,6 +11,7 @@ daemon.log
 daemon.pid
 bd.sock
 sync-state.json
+last-touched
 
 # Local version tracking (prevents upgrade notification spam after git ops)
 .local_version

internal/merge/merge.go

@@ -61,6 +61,8 @@ type Issue struct {
 	DeletedBy    string `json:"deleted_by,omitempty"`    // Who deleted the issue
 	DeleteReason string `json:"delete_reason,omitempty"` // Why the issue was deleted
 	OriginalType string `json:"original_type,omitempty"` // Issue type before deletion
+	// HOP quality field
+	QualityScore *float32 `json:"quality_score,omitempty"` // Aggregate quality (0.0-1.0)
 }
 
 // Dependency represents an issue dependency