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

app/Providers/Filament/AdminPanelProvider.php

@@ -48,41 +48,6 @@ class AdminPanelProvider extends PanelProvider
             ->sidebarWidth('13rem')
             ->maxContentWidth(\Filament\Support\Enums\Width::Full)
             ->userMenuItems([
-                // 工具：同步旧站数据（sablog 增量导入，约 1 分钟）
-                \Filament\Actions\Action::make('sablog-import')
-                    ->label('同步旧站数据')
-                    ->icon('heroicon-o-arrow-path')
-                    ->color('info')
-                    ->requiresConfirmation()
-                    ->modalDescription('从旧 sablog 库增量导入文章/评论/标签等（幂等，不会产生重复），约需 1 分钟，期间请不要重复点击。')
-                    ->action(function (): void {
-                        $src = config('blog.sablog_source');
-                        try {
-                            \Illuminate\Support\Facades\Artisan::call('sablog:import', [
-                                '--host' => $src['host'],
-                                '--port' => $src['port'],
-                                '--database' => $src['database'],
-                                '--username' => $src['username'],
-                                '--password' => $src['password'],
-                                '--prefix' => $src['prefix'],
-                            ]);
-                            $output = trim(\Illuminate\Support\Facades\Artisan::output());
-                            \App\Blog\Support\PageCacheMiddleware::flush();
-                            \Filament\Notifications\Notification::make()
-                                ->title('旧站数据同步完成')
-                                ->body(\Illuminate\Support\Str::afterLast($output, '报告：') ?: $output)
-                                ->success()
-                                ->persistent()
-                                ->send();
-                        } catch (\Throwable $e) {
-                            \Filament\Notifications\Notification::make()
-                                ->title('同步失败')
-                                ->body($e->getMessage())
-                                ->danger()
-                                ->persistent()
-                                ->send();
-                        }
-                    }),
                 // 工具：清空缓存（Livewire action，即时通知）
                 \Filament\Actions\Action::make('flush-page-cache')
                     ->label('清空前台缓存')