feat: Add multi-language support (i18n)

Languages supported (8):
- English (en)
- 日本語 (ja)
- Deutsch (de)
- Français (fr)
- Español (es)
- 简体中文 (zh-CN)
- 繁體中文 (zh-TW)
- 한국어 (ko)

Changes:
- Add locale column to users table
- Add SetLocale middleware for automatic locale detection
- Add LocaleController for language switching
- Create language files with translations for all UI elements
- Add language selector to user profile page
- Update all Blade views to use translation strings

src/resources/views/livewire/quick-switcher.blade.php

@@ -51,7 +51,7 @@ class="w-full max-w-2xl bg-white rounded-lg shadow-2xl"
                             type="text"
                             wire:model.live="search"
                             class="w-full pl-10 pr-4 py-3 border-0 focus:ring-0 text-lg"
-                            placeholder="Search documents..."
+                            placeholder="{{ __('messages.quick_switcher.placeholder') }}"
                             autocomplete="off"
                         >
                     </div>
@@ -61,7 +61,7 @@ class="w-full pl-10 pr-4 py-3 border-0 focus:ring-0 text-lg"
                 <div class="max-h-96 overflow-y-auto">
                     @if(empty($this->results))
                         <div class="p-8 text-center text-gray-500">
-                            No documents found
+                            {{ __('messages.quick_switcher.no_results') }}
                         </div>
                     @else
                         <ul class="divide-y divide-gray-200">
@@ -109,15 +109,15 @@ class="block px-4 py-3 hover:bg-gray-50 transition {{ $index === $selectedIndex
                             <span class="flex items-center">
                                 <kbd class="px-2 py-1 bg-white border border-gray-300 rounded text-xs font-semibold mr-1">↑</kbd>
                                 <kbd class="px-2 py-1 bg-white border border-gray-300 rounded text-xs font-semibold mr-2">↓</kbd>
-                                to navigate
+                                {{ __('messages.quick_switcher.navigate') }}
                             </span>
                             <span class="flex items-center">
                                 <kbd class="px-2 py-1 bg-white border border-gray-300 rounded text-xs font-semibold mr-2">↵</kbd>
-                                to select
+                                {{ __('messages.quick_switcher.select') }}
                             </span>
                             <span class="flex items-center">
                                 <kbd class="px-2 py-1 bg-white border border-gray-300 rounded text-xs font-semibold mr-2">esc</kbd>
-                                to close
+                                {{ __('messages.quick_switcher.close') }}
                             </span>
                         </div>
                     </div>