fix: stub hook send in tests for CI without /dev/tty

Avoid opening /dev/tty during unit tests so GitHub Actions can run
go test without a controlling terminal.

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

internal/hook/stdin_test.go

@@ -5,9 +5,26 @@ import (
 	"testing"
 
 	"github.com/longbin/agent-notify/internal/config"
+	"github.com/longbin/agent-notify/internal/notify"
 )
 
+func stubCursorSend(t *testing.T) {
+	t.Helper()
+	t.Setenv("HOME", t.TempDir())
+	prevHook := sendForHook
+	prevAuto := sendAuto
+	sendForHook = func(string, string, string) (notify.SendResult, error) {
+		return notify.SendResult{Method: "test"}, nil
+	}
+	sendAuto = sendForHook
+	t.Cleanup(func() {
+		sendForHook = prevHook
+		sendAuto = prevAuto
+	})
+}
+
 func TestRunCursorEmptyStdinDoesNotBlock(t *testing.T) {
+	stubCursorSend(t)
 	cfg := config.Default()
 	err := RunCursor(bytes.NewReader(nil), cfg, "stop", nil)
 	if err != nil {
@@ -16,6 +33,7 @@ func TestRunCursorEmptyStdinDoesNotBlock(t *testing.T) {
 }
 
 func TestRunCursorWithPayload(t *testing.T) {
+	stubCursorSend(t)
 	cfg := config.Default()
 	err := RunCursor(bytes.NewReader([]byte(`{"workspace_roots":["/tmp/proj"]}`)), cfg, "stop", nil)
 	if err != nil {