fix(webui): build support bundle synchronously on download, bypass task queue

Support bundle is now built on-the-fly when the user clicks the button,
regardless of whether other tasks are running:

- GET /export/support.tar.gz builds the bundle synchronously and streams it
  directly to the client; the temp archive is removed after serving
- Remove POST /api/export/bundle and handleAPIExportBundle — the task-queue
  approach meant the bundle could only be downloaded after navigating away
  and back, and was blocked entirely while a long SAT test was running
- UI: single "Download Support Bundle" button; fetch+blob gives a loading
  state ("Building...") while the server collects logs, then triggers the
  browser download with the correct filename from Content-Disposition

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/api_test.go

@@ -1,7 +1,6 @@
 package webui
 
 import (
-	"encoding/json"
 	"net/http/httptest"
 	"strings"
 	"testing"
@@ -65,42 +64,6 @@ func TestHandleAPISATRunDecodesBodyWithoutContentLength(t *testing.T) {
 	}
 }
 
-func TestHandleAPIExportBundleQueuesTask(t *testing.T) {
-	globalQueue.mu.Lock()
-	originalTasks := globalQueue.tasks
-	globalQueue.tasks = nil
-	globalQueue.mu.Unlock()
-	t.Cleanup(func() {
-		globalQueue.mu.Lock()
-		globalQueue.tasks = originalTasks
-		globalQueue.mu.Unlock()
-	})
-
-	h := &handler{opts: HandlerOptions{ExportDir: t.TempDir()}}
-	req := httptest.NewRequest("POST", "/api/export/bundle", nil)
-	rec := httptest.NewRecorder()
-
-	h.handleAPIExportBundle(rec, req)
-
-	if rec.Code != 200 {
-		t.Fatalf("status=%d body=%s", rec.Code, rec.Body.String())
-	}
-	var body map[string]string
-	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
-		t.Fatalf("decode response: %v", err)
-	}
-	if body["task_id"] == "" {
-		t.Fatalf("missing task_id in response: %v", body)
-	}
-	globalQueue.mu.Lock()
-	defer globalQueue.mu.Unlock()
-	if len(globalQueue.tasks) != 1 {
-		t.Fatalf("tasks=%d want 1", len(globalQueue.tasks))
-	}
-	if got := globalQueue.tasks[0].Target; got != "support-bundle" {
-		t.Fatalf("target=%q want support-bundle", got)
-	}
-}
 
 func TestPushFanRingsTracksByNameAndCarriesForwardMissingSamples(t *testing.T) {
 	h := &handler{}