Fix async function call for load_plan_for_run_with_fallback

Use await directly instead of asyncio.to_thread() since the
function is already async.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

server.py

@@ -1437,7 +1437,7 @@ async def run_plan_node_detail(run_id: str, step_id: str, request: Request):
         return HTMLResponse(f'<p class="text-red-400">Run not found</p>', status_code=404)
 
     # Load plan data (with fallback to generate from recipe)
-    plan_data = await asyncio.to_thread(load_plan_for_run_with_fallback, run)
+    plan_data = await load_plan_for_run_with_fallback(run)
 
     if not plan_data:
         return HTMLResponse('<p class="text-gray-400">Plan not found</p>')
@@ -1584,7 +1584,7 @@ async def run_plan_visualization(run_id: str, request: Request, node: Optional[s
         return HTMLResponse(render_page("Access Denied", content, ctx.actor_id, active_tab="runs"), status_code=403)
 
     # Load plan data (with fallback to generate from recipe)
-    plan_data = await asyncio.to_thread(load_plan_for_run_with_fallback, run)
+    plan_data = await load_plan_for_run_with_fallback(run)
 
     # Build sub-navigation tabs
     tabs_html = render_run_sub_tabs(run_id, active="plan")