fix: Improve startup time with proper settings loading.

* Avoid doing duplicate calls to setings_load_subtree, which iterates
  NVS fully each time under the hood, and instead use on settings_load
  later in the lifecycle.

app/src/main.c

@@ -24,6 +24,11 @@ int main(void) {
         return -ENOTSUP;
     }
 
+#if IS_ENABLED(CONFIG_SETTINGS)
+    settings_subsys_init();
+    settings_load();
+#endif
+
 #ifdef CONFIG_ZMK_DISPLAY
     zmk_display_init();
 #endif /* CONFIG_ZMK_DISPLAY */