Enable language switching for guest users

Changes:
- Move locale.update route outside auth middleware
- Update LocaleController to support both authenticated and guest users
  - Guest users: Save locale preference to session only
  - Authenticated users: Save to both session and database
- Add language switcher dropdown to header for all users
  - Display current language with globe icon
  - Show all 8 supported languages in dropdown
  - Highlight currently selected language with checkmark

This allows non-logged-in users to change the interface language,
improving accessibility for international visitors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/resources/views/layouts/knowledge-base.blade.php

@@ -59,6 +59,51 @@ class="inline-flex items-center px-3 py-2 border border-gray-300 shadow-sm text-
                                 </kbd>
                             </button>
 
+                            <!-- Language Switcher (for all users) -->
+                            <div x-data="{ open: false }" @click.away="open = false" class="relative">
+                                <button
+                                    @click="open = !open"
+                                    class="flex items-center px-3 py-2 text-sm font-medium text-gray-700 hover:text-gray-900 focus:outline-none"
+                                    title="{{ __('messages.settings.change_language') }}"
+                                >
+                                    <svg class="w-5 h-5 mr-1" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                                        <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M3 5h12M9 3v2m1.048 9.5A18.022 18.022 0 016.412 9m6.088 9h7M11 21l5-10 5 10M12.751 5C11.783 10.77 8.07 15.61 3 18.129"></path>
+                                    </svg>
+                                    @php
+                                        $currentLocale = app()->getLocale();
+                                        $locales = \App\Http\Middleware\SetLocale::SUPPORTED_LOCALES;
+                                    @endphp
+                                    <span class="hidden sm:inline">{{ $locales[$currentLocale] ?? 'English' }}</span>
+                                    <svg class="ml-1 h-4 w-4" fill="currentColor" viewBox="0 0 20 20">
+                                        <path fill-rule="evenodd" d="M5.293 7.293a1 1 0 011.414 0L10 10.586l3.293-3.293a1 1 0 111.414 1.414l-4 4a1 1 0 01-1.414 0l-4-4a1 1 0 010-1.414z" clip-rule="evenodd"></path>
+                                    </svg>
+                                </button>
+
+                                <div
+                                    x-show="open"
+                                    x-transition
+                                    class="absolute right-0 mt-2 w-48 bg-white rounded-md shadow-lg py-1 ring-1 ring-black ring-opacity-5 max-h-96 overflow-y-auto"
+                                >
+                                    @foreach($locales as $code => $name)
+                                        <form method="POST" action="{{ route('locale.update') }}" class="inline-block w-full">
+                                            @csrf
+                                            <input type="hidden" name="locale" value="{{ $code }}">
+                                            <button
+                                                type="submit"
+                                                class="w-full text-left px-4 py-2 text-sm hover:bg-gray-100 {{ $currentLocale === $code ? 'bg-indigo-50 text-indigo-700 font-semibold' : 'text-gray-700' }}"
+                                            >
+                                                {{ $name }}
+                                                @if($currentLocale === $code)
+                                                    <svg class="inline-block w-4 h-4 ml-2" fill="currentColor" viewBox="0 0 20 20">
+                                                        <path fill-rule="evenodd" d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z" clip-rule="evenodd"></path>
+                                                    </svg>
+                                                @endif
+                                            </button>
+                                        </form>
+                                    @endforeach
+                                </div>
+                            </div>
+
                             @auth
                                 <!-- User Dropdown -->
                                 <div x-data="{ open: false }" @click.away="open = false" class="relative">