feat: show warning when running main branch build (#13462)

* feat: show warning when running main branch build

* fix: emoji weirdness

* fix: use icon instead of emoji

* fix: missing conditional

web/src/lib/components/shared-components/server-about-modal.svelte

@@ -4,6 +4,8 @@
   import { type ServerAboutResponseDto, type ServerVersionHistoryResponseDto } from '@immich/sdk';
   import { DateTime } from 'luxon';
   import { t } from 'svelte-i18n';
+  import { mdiAlert } from '@mdi/js';
+  import Icon from '$lib/components/elements/icon.svelte';
 
   export let onClose: () => void;
 
@@ -152,6 +154,15 @@
         </div>
       {/if}
 
+      {#if info.sourceRef === 'main' && info.repository === 'immich-app/immich'}
+        <div class="col-span-full p-4 flex gap-1">
+          <Icon path={mdiAlert} size="2em" color="#ffcc4d" />
+          <p class="immich-form-label text-sm" id="main-warning">
+            {$t('main_branch_warning')}
+          </p>
+        </div>
+      {/if}
+
       <div class="col-span-full">
         <label class="font-medium text-immich-primary dark:text-immich-dark-primary text-sm" for="version-history"
           >{$t('version_history')}</label