feat: add scoped browser stop and job control

internal/platform/browser/job_other.go

@@ -0,0 +1,24 @@
+//go:build !windows
+
+package browser
+
+import (
+	"context"
+	"errors"
+	"os"
+)
+
+type jobHandle struct{}
+
+func (jobHandle) assign(*os.Process) error { return nil }
+func (jobHandle) close()                   {}
+
+func (p *osProcess) Stop(ctx context.Context, force bool) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	if !force {
+		return errors.New("graceful browser close is only supported on Windows")
+	}
+	return p.command.Process.Kill()
+}