fix: defer config error toast to session.created for TUI readiness (#286)

* fix: defer config error toast to session.created for TUI readiness

Removed showToast calls from loadConfigFromPath() function. Error notifications were not visible during plugin initialization because the TUI was not ready yet.

Changes:
- Removed immediate showToast calls from validation error handler
- Removed immediate showToast calls from file load error handler
- Errors are still captured via addConfigLoadError() for later display
- auto-update-checker hook will display errors via showConfigErrorsIfAny() after session.created event

This ensures error messages are displayed when the TUI is fully ready and able to render them properly.

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

* fix: await config error toast before showing startup toast

Ensure config errors are awaited and displayed before the startup spinner toast is shown. Changed showConfigErrorsIfAny(ctx).catch(() => {}) to await showConfigErrorsIfAny(ctx) to guarantee proper error handling order.

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/hooks/auto-update-checker/index.ts

@@ -34,12 +34,12 @@ export function createAutoUpdateCheckerHook(ctx: PluginInput, options: AutoUpdat
 
       hasChecked = true
 
-      setTimeout(() => {
+      setTimeout(async () => {
         const cachedVersion = getCachedVersion()
         const localDevVersion = getLocalDevVersion(ctx.directory)
         const displayVersion = localDevVersion ?? cachedVersion
 
-        showConfigErrorsIfAny(ctx).catch(() => {})
+        await showConfigErrorsIfAny(ctx)
 
         if (localDevVersion) {
           if (showStartupToast) {