feat(mma): Complete Visual DAG implementation, fix link creation/deletion, and sync docs

conductor/product.md

@@ -31,7 +31,7 @@ For deep implementation details when planning or implementing tracks, consult `d
   - **MMA Delegation Engine:** Route tasks, ensuring role-scoped context and detailed observability via timestamped sub-agent logs. Supports dynamic ticket creation and dependency resolution via an automated Dispatcher Loop.
   - **MMA Observability Dashboard:** A high-density control center within the GUI for monitoring and managing the 4-Tier architecture.
     - **Track Browser:** Real-time visualization of all implementation tracks with status indicators and progress bars.
-    - **Hierarchical Task DAG:** An interactive, tree-based visualizer for the active track's task dependencies, featuring color-coded state tracking (Ready, Running, Blocked, Done) and manual retry/skip overrides.
+    - **Visual Task DAG:** An interactive, node-based visualizer for the active track's task dependencies using `imgui-node-editor`. Features color-coded state tracking (Ready, Running, Blocked, Done), drag-and-drop dependency creation, and right-click deletion.
     - **Strategy Visualization:** Dedicated real-time output streams for Tier 1 (Strategic Planning) and Tier 2/3 (Execution) agents, allowing the user to follow the agent's reasoning chains alongside the task DAG.
   - **Track-Scoped State Management:** Segregates discussion history and task progress into per-track state files (e.g., `conductor/tracks/<track_id>/state.toml`). This prevents global context pollution and ensures the Tech Lead session is isolated to the specific track's objective.
   **Native DAG Execution Engine:** Employs a Python-based Directed Acyclic Graph (DAG) engine to manage complex task dependencies. Supports automated topological sorting, robust cycle detection, and **transitive blocking propagation** (cascading `blocked` status to downstream dependents to prevent execution stalls).