fix: move initPresets to onMounted and prevent saving default preset

Address CodeRabbit review findings:
- Move fire-and-forget initPresets() call into onMounted lifecycle hook
- Skip savePreset when switching away from default preset to avoid
  writing keybindings/default.json

src/components/dialog/content/setting/KeybindingPanel.vue

@@ -161,7 +161,7 @@ import Dialog from 'primevue/dialog'
 import InputText from 'primevue/inputtext'
 import Message from 'primevue/message'
 import Tag from 'primevue/tag'
-import { computed, ref, watchEffect } from 'vue'
+import { computed, onMounted, ref, watchEffect } from 'vue'
 import { useI18n } from 'vue-i18n'
 
 import DropdownMenu from '@/components/common/DropdownMenu.vue'
@@ -210,7 +210,7 @@ async function initPresets() {
   }
 }
 
-initPresets()
+onMounted(() => initPresets())
 
 // "..." menu entries (teleported to header)
 async function saveAsNewPreset() {

src/platform/keybindings/presetService.ts

@@ -161,7 +161,7 @@ export function useKeybindingPresetService() {
       })
 
       if (result === null) return
-      if (result) {
+      if (result && keybindingStore.currentPresetName !== 'default') {
         await savePreset(keybindingStore.currentPresetName)
       }
     }