fix: clear search when adding a step from the tool picker

When a tool was selected via search, the search text persisted after
the picker closed. Reopening the picker showed a filtered list instead
of all tools, making it look like clicking tools without searching
didn't work.

apps/web/src/components/tools/pipeline-builder.tsx

@@ -107,6 +107,7 @@ export function PipelineBuilder({
       };
       onStepsChange([...steps, step]);
       setShowToolPicker(false);
+      setToolSearch("");
       setExpandedStep(step.id);
     },
     [steps, onStepsChange],