fix(flowpilot): fix broken height chain hiding action bar (Resolve/Escalate/Pause)

The FlowPilotSession component uses h-full flex-col to position the action
bar at the bottom, but its parent div in FlowPilotSessionPage only had
flex-1 min-h-0 without flex flex-col. This broke the height chain, causing
the action bar to render below the visible area.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/pages/FlowPilotSessionPage.tsx

@@ -161,7 +161,7 @@ export default function FlowPilotSessionPage() {
       </div>
 
       {/* Session content */}
-      <div className="flex-1 min-h-0">
+      <div className="flex-1 min-h-0 flex flex-col">
         <FlowPilotSession
           session={fp.session}
           allSteps={fp.allSteps}