feat: topbar legacy-sync button, card view mode with cover fallback, year/month/day archives, richer page cache admin, stylevar repeater editor

- topbar: Livewire LegacySyncButton next to 写文章 (moved from user menu)
- view modes: add 图文(card) grid with cover fallback chain (cover → attachment → first content image → placeholder); list mode now title-only compact
- archives: year/month/day index grid
- page cache admin: size + expiry columns, total size, cache policy note
- theme inject: stylevars switch from KeyValue to Repeater with multi-line HTML editing
- import: html_entity_decode for category/post-title/link/keywords/comment author

resources/views/filament/hooks/topbar-tools.blade.php

@@ -31,4 +31,6 @@
     >
         写文章
     </x-filament::button>
+
+    <livewire:legacy-sync-button />
 </div>