fix(sim): wire btn_approve_script and expose pending_script_approval in hook API

_handle_approve_script existed but was not registered in the click handler dict.
_pending_dialog (PowerShell confirmation) was invisible to the hook API —
only _pending_ask_dialog (MCP tool ask) was exposed.

- gui_2.py: register btn_approve_script -> _handle_approve_script
- api_hooks.py: add pending_script_approval field to mma_status response
- visual_sim_mma_v2.py: _drain_approvals handles pending_script_approval

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/visual_sim_mma_v2.py

@@ -25,6 +25,10 @@ def _drain_approvals(client: ApiHookClient, status: dict) -> None:
         print('[SIM] Approving pending tool...')
         client.click('btn_approve_tool')
         time.sleep(0.5)
+    elif status.get('pending_script_approval'):
+        print('[SIM] Approving pending PowerShell script...')
+        client.click('btn_approve_script')
+        time.sleep(0.5)
 
 
 def _poll(client: ApiHookClient, timeout: int, condition, label: str) -> tuple[bool, dict]: