feat(sessions): default filter to current app when entering session page

Navigate directly to the active app's sessions instead of showing all.

src/App.tsx

@@ -724,7 +724,7 @@ function App() {
           );
 
         case "sessions":
-          return <SessionManagerPage />;
+          return <SessionManagerPage key={activeApp} appId={activeApp} />;
         case "workspace":
           return <WorkspaceFilesPanel />;
         case "openclawEnv":