Add placeholder images, enhance alert styles, and implement theme toggle component with dark mode support

app/Livewire/ThemeToggleComponent.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Livewire;
+
+use Livewire\Component;
+
+class ThemeToggleComponent extends Component
+{
+    public bool $isDark = false;
+
+    public function mount()
+    {
+        $this->isDark = session('theme') === 'dark';
+    }
+
+    public function toggleTheme()
+    {
+        $this->isDark = !$this->isDark;
+        session(['theme' => $this->isDark ? 'dark' : 'light']);
+        $this->dispatch('theme-changed', theme: $this->isDark ? 'dark' : 'light');
+    }
+
+    public function render()
+    {
+        return view('livewire.theme-toggle-component');
+    }
+}