feat: add admin env badge, quick post button, and harden plugin enable

Show local/prod in the Filament topbar, jump to create post in one click, tighten sidebar spacing, and stop Hello World from 500ing when its tables are missing.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/Feature/AdminPagesTest.php

@@ -71,4 +71,36 @@ class AdminPagesTest extends TestCase
     {
         $this->get('/admin')->assertRedirect('/admin/login');
     }
+
+    public function test_admin_environment_maps_production_to_prod(): void
+    {
+        $original = app()->environment();
+        app()['env'] = 'production';
+
+        $this->assertSame('prod', \App\Filament\Support\AdminEnvironment::name());
+        $this->assertSame('danger', \App\Filament\Support\AdminEnvironment::color());
+
+        app()['env'] = $original;
+    }
+
+    public function test_admin_topbar_shows_environment_and_create_post_button(): void
+    {
+        $this->actingAs($this->admin)
+            ->get('/admin')
+            ->assertOk()
+            ->assertSee(\App\Filament\Support\AdminEnvironment::name(), false)
+            ->assertSee('写文章', false)
+            ->assertSee('/admin/posts/create', false);
+    }
+
+    public function test_hello_world_plugin_pages_load_when_enabled(): void
+    {
+        $manager = app(\App\Blog\Support\PluginManager::class);
+        $manager->enable('demo.hello-world');
+        \Plugins\Demo\HelloWorld\ServiceProvider::bootPlugin($manager);
+
+        $this->actingAs($this->admin)->get('/admin')->assertOk();
+        $this->actingAs($this->admin)->get('/admin/posts/create')->assertOk();
+        $this->get('/hello-world')->assertOk();
+    }
 }