feat(mma): Implement ExecutionEngine with auto-queue and step-mode support

dag_engine.py

@@ -76,3 +76,50 @@ class TrackDAG:
             visit(ticket.id)
 
         return stack
+
+class ExecutionEngine:
+    def __init__(self, dag: TrackDAG, auto_queue: bool = False):
+        self.dag = dag
+        self.auto_queue = auto_queue
+
+    def tick(self) -> List[Ticket]:
+        """
+        Returns a list of tasks that are currently 'ready' to be executed.
+        A task is ready if its status is 'todo' and all its dependencies are 'completed'.
+        If auto_queue=True, it will automatically mark 'ready' tasks as 'in-progress',
+        unless step_mode=True is set on the task.
+        """
+        ready = self.dag.get_ready_tasks()
+        
+        if self.auto_queue:
+            for ticket in ready:
+                if not ticket.step_mode:
+                    ticket.status = "in_progress"
+        
+        return ready
+
+    def approve_task(self, task_id: str):
+        """
+        Manually approves a task to move it to 'in_progress'.
+        Typically used for tasks with step_mode=True or when auto_queue is False.
+        """
+        ticket = self.dag.ticket_map.get(task_id)
+        if ticket and ticket.status == "todo":
+            # Check if dependencies are met first
+            all_done = True
+            for dep_id in ticket.depends_on:
+                dep = self.dag.ticket_map.get(dep_id)
+                if not dep or dep.status != "completed":
+                    all_done = False
+                    break
+            
+            if all_done:
+                ticket.status = "in_progress"
+
+    def update_task_status(self, task_id: str, status: str):
+        """
+        Updates the status of a specific task within the DAG.
+        """
+        ticket = self.dag.ticket_map.get(task_id)
+        if ticket:
+            ticket.status = status