webui: add "6. Scenario" page — run scriptable test scenarios from removable media through the normal task queue

Exposes the scenario engine (platform.System.RunScenario, added earlier)
in the web UI instead of only the `bee run` CLI: a new nav item lists every
scenarios/*.json found on mounted removable media (GET /api/scenario/list)
and runs one with a click (POST /api/scenario/run), enqueued as a normal
Task with target "scenario" — progress/logs live in Tasks like any other
SAT pack, no separate live-output UI needed.

- app.go: satRunner gains RunScenario, exportManager gains
  ListScenarioFilesOnRemovableMedia/ReadScenarioFromRemovableMedia — both
  already implemented on platform.System, just newly exposed through App.
- webui/tasks.go: taskParams.ScenarioName; runTask's "scenario" case reads
  the file from removable media, parses it, and runs it.
- webui/page_scenario.go: the page itself.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

audit/internal/webui/tasks.go

@@ -148,6 +148,7 @@ type taskParams struct {
 	RAIDDevices        []string     `json:"raid_devices,omitempty"`
 	RAIDArrayName      string       `json:"raid_array_name,omitempty"`
 	RAIDSlot           string       `json:"raid_slot,omitempty"`
+	ScenarioName       string       `json:"scenario_name,omitempty"`
 }
 
 type persistedTask struct {
@@ -988,6 +989,22 @@ func (q *taskQueue) runTask(t *Task, j *jobState, ctx context.Context) {
 			break
 		}
 		archive, err = a.RunNCCLTests(ctx, "", t.params.GPUIndices, j.append)
+	case "scenario":
+		if a == nil {
+			err = fmt.Errorf("app not configured")
+			break
+		}
+		var data []byte
+		data, err = a.ReadScenarioFromRemovableMedia(t.params.ScenarioName)
+		if err != nil {
+			break
+		}
+		var spec platform.ScenarioSpec
+		spec, err = platform.ParseScenarioJSON(data)
+		if err != nil {
+			break
+		}
+		archive, err = a.RunScenario(ctx, "", spec, j.append)
 	case "nvidia-stress":
 		if a == nil {
 			err = fmt.Errorf("app not configured")