feat(bar): 新增 tray_output_index 配置用于选择 tray 挂载的屏幕

include/zdwm/bar.h

@@ -39,6 +39,8 @@ typedef struct zdwm_bar_config_t {
   const char *binding_mode_bg;
   const char *binding_mode_fg;
 
+  int32_t tray_output_index;
+
   uint32_t window_padding_x;
   const char *window_bg;
   const char *window_fg;

src/runtime/runtime.c

@@ -120,8 +120,9 @@ static void runtime_init_bar(runtime_t *runtime) {
       .height = bar_height,
     };
     auto color = bar->palette.bg.argb;
+    bool enable_tray = (int32_t)i == bar->config.tray_output_index;
     auto bar_window =
-      backend_create_bar_window(backend, bar_rect, color, false);
+      backend_create_bar_window(backend, bar_rect, color, enable_tray);
     bar->tray = bar_window.tray;
     auto bar_output = &bar->bars[i];
     bar_output->cr = bar_window.cr;