M2: 主题系统（sablog经典+modern简约）+ 前台全部页面 + 老 URL 301 兼容 + markdown 双份导入

app/Blog/Providers/ThemeServiceProvider.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace App\Blog\Providers;
+
+use App\Blog\Support\ThemeManager;
+use App\Blog\View\Composers\SidebarComposer;
+use Illuminate\Support\Facades\File;
+use Illuminate\Support\Facades\View;
+use Illuminate\Support\ServiceProvider;
+
+class ThemeServiceProvider extends ServiceProvider
+{
+    public function register(): void
+    {
+        $this->app->singleton(ThemeManager::class);
+    }
+
+    public function boot(): void
+    {
+        // 激活主题的 views 目录前置到全局视图路径，实现主题覆盖 + 默认兜底
+        $this->prependActiveThemeViews();
+
+        // 侧边栏数据共享：所有前台视图自动获得 $categories/$recentPosts/$hotTags/$links 等
+        View::composer(
+            ['index', 'show', 'list', 'archives', 'tags', 'tag', 'search', 'links', 'comments', 'login', 'register', 'profile'],
+            SidebarComposer::class
+        );
+    }
+
+    private function prependActiveThemeViews(): void
+    {
+        $manager = app(ThemeManager::class);
+        $views = $manager->path($manager->active()).'/views';
+
+        if (! is_dir($views)) {
+            return;
+        }
+
+        $paths = config('view.paths');
+        array_unshift($paths, $views);
+        config(['view.paths' => $paths]);
+        app('view')->getFinder()->setPaths($paths);
+    }
+}