Log failure-notification timing and plan faster Windows toasts.

Append app-side delays to logs/notify-timing.log, add a PowerShell baseline
script (~773 ms), and track native WinRT toasts in ROADMAP.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/ui/notify_timing.go

@@ -0,0 +1,69 @@
+package ui
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+const notificationTimingLogName = "notify-timing.log"
+
+// notificationTiming captures wall-clock points from a failed run through
+// SendNotification. It does not include OS toast display latency — Fyne on
+// Windows shows toasts via a separate PowerShell process after SendNotification
+// returns.
+type notificationTiming struct {
+	JobName     string
+	RunFinished time.Time
+	EmittedAt   time.Time
+	UIQueuedAt  time.Time
+	AfterSendAt time.Time
+}
+
+func (t notificationTiming) formatLine() string {
+	return fmt.Sprintf(
+		"%s\tjob=%s\tms_after_run=%s\tms_fyne_do=%s\tms_send=%s\tms_app_total=%s\n",
+		t.AfterSendAt.Format(time.RFC3339Nano),
+		t.JobName,
+		msBetween(t.RunFinished, t.EmittedAt),
+		msBetween(t.EmittedAt, t.UIQueuedAt),
+		msBetween(t.UIQueuedAt, t.AfterSendAt),
+		msBetween(t.EmittedAt, t.AfterSendAt),
+	)
+}
+
+func msBetween(from, to time.Time) string {
+	if from.IsZero() || to.IsZero() || to.Before(from) {
+		return "-"
+	}
+	return fmt.Sprintf("%d", to.Sub(from).Milliseconds())
+}
+
+func appendNotificationTimingLog(logsDir string, timing notificationTiming) error {
+	if logsDir == "" {
+		return nil
+	}
+	if err := os.MkdirAll(logsDir, 0o755); err != nil {
+		return err
+	}
+	path := filepath.Join(logsDir, notificationTimingLogName)
+	file, err := os.OpenFile(path, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	info, err := file.Stat()
+	if err != nil {
+		return err
+	}
+	if info.Size() == 0 {
+		if _, err := file.WriteString("# GoSentry failure-notification timing (app side only; OS toast delay is not included)\n" +
+			"# columns: timestamp job ms_after_run ms_fyne_do ms_send ms_app_total\n"); err != nil {
+			return err
+		}
+	}
+	_, err = file.WriteString(timing.formatLine())
+	return err
+}