fix: Remove extra_vars parameter from resolve_placeholders call - function doesn't support it yet

backend/workflow_executor.py

@@ -315,9 +315,9 @@ async def load_prompt_template(prompt_slug: str, context: Dict[str, Any]) -> str
     profile_id = context.get("profile_id")
     resolved = resolve_placeholders(
         template=template,
-        profile_id=profile_id,
-        extra_vars=context.get("variables", {})
+        profile_id=profile_id
     )
+    # TODO Phase 3: Support custom variables from workflow context
 
     return resolved