Release validation: tests green, USB pack, fleet UX and API hardening.

Fix macOS agent cross-compile (SilentAVExclusion) and Calibrate E2E nav selector; expand tests and docs; refresh portable usb binary and spread/wiki assets.

server/internal/cloudflared/launcher_windows_test.go

@@ -0,0 +1,17 @@
+//go:build windows
+
+package cloudflared
+
+import "testing"
+
+func TestStartEmptyTokenIsNoOp(t *testing.T) {
+	for _, token := range []string{"", "  ", "\t", `""`, "''"} {
+		if err := Start("", "", token); err != nil {
+			t.Fatalf("Start(%q): %v", token, err)
+		}
+	}
+}
+
+func TestStopWhenNotRunning(t *testing.T) {
+	Stop()
+}