feat(vwb): execute wait for state

visual_workflow_builder/backend/contracts/action_contracts.py

@@ -198,6 +198,22 @@ VWB_ACTION_CONTRACTS: Dict[str, ActionContract] = {
         optional_params=["wait_mode", "max_wait_time_ms", "check_interval_ms"],
         param_validators={"visual_anchor": lambda p: has_visual_anchor({"visual_anchor": p})}
     ),
+    "wait_for_state": ActionContract(
+        action_type="wait_for_state",
+        description="Attendre qu'un etat semantique d'ecran soit observe",
+        required_params=["expected_state"],
+        optional_params=["timeout_ms", "poll_interval_ms", "evidence_required"],
+        param_validators={
+            "expected_state": lambda p: isinstance(p, dict) and any(
+                p.get(key)
+                for key in (
+                    "window_title_in",
+                    "window_title_contains",
+                    "process_active",
+                )
+            )
+        }
+    ),
 
     # --- ACTIONS DE SCROLL ---
     "scroll_to_anchor": ActionContract(