feat(ready): add --type flag for filtering by issue type (gt-ktf3)

Enables bd ready --type=merge-request for MQ integration.
The Engineer can now query for ready merge-requests.

Files changed:
- cmd/bd/ready.go: Add -t/--type flag
- internal/types/types.go: Add Type field to WorkFilter
- internal/rpc/protocol.go: Add Type to ReadyArgs
- internal/storage/sqlite/ready.go: Filter by issue_type column

internal/storage/sqlite/ready.go

@@ -27,6 +27,12 @@ func (s *SQLiteStorage) GetReadyWork(ctx context.Context, filter types.WorkFilte
 		args = append(args, filter.Status)
 	}
 
+	// Filter by issue type (gt-ktf3: MQ integration)
+	if filter.Type != "" {
+		whereClauses = append(whereClauses, "i.issue_type = ?")
+		args = append(args, filter.Type)
+	}
+
 	if filter.Priority != nil {
 		whereClauses = append(whereClauses, "i.priority = ?")
 		args = append(args, *filter.Priority)