Add complete Laravel LLM Gateway implementation

Core Features:
- Multi-provider support (OpenAI, Anthropic, DeepSeek, Gemini, Mistral)
- Provider service architecture with abstract base class
- Dynamic model discovery from provider APIs
- Encrypted per-user provider credentials storage

Admin Interface:
- Complete admin panel with Livewire components
- User management with CRUD operations
- API key management with testing capabilities
- Budget system with limits and reset schedules
- Usage logs with filtering and CSV export
- Model pricing management with cost calculator
- Dashboard with Chart.js visualizations

Database Schema:
- MariaDB migrations for all tables
- User provider credentials (encrypted)
- LLM request logging
- Budget tracking and rate limiting
- Model pricing configuration

API Implementation:
- OpenAI-compatible endpoints
- Budget checking middleware
- Rate limit enforcement
- Request logging jobs
- Cost calculation service

Testing:
- Unit tests for all provider services
- Provider factory tests
- Cost calculator tests

Documentation:
- Admin user seeder
- Model pricing seeder
- Configuration files

laravel-app/app/Services/LLM/ProviderFactory.php

@@ -0,0 +1,62 @@
+<?php
+
+namespace App\Services\LLM;
+
+use App\Services\LLM\Contracts\ProviderInterface;
+use App\Services\LLM\Providers\{
+    OpenAIProvider,
+    AnthropicProvider,
+    MistralProvider,
+    GeminiProvider,
+    DeepSeekProvider
+};
+
+class ProviderFactory
+{
+    /**
+     * Create a provider instance
+     *
+     * @param string $provider Provider name (openai, anthropic, mistral, gemini, deepseek)
+     * @param string $apiKey API key for the provider
+     * @return ProviderInterface
+     * @throws \InvalidArgumentException
+     */
+    public static function create(string $provider, string $apiKey): ProviderInterface
+    {
+        return match (strtolower($provider)) {
+            'openai' => new OpenAIProvider($apiKey),
+            'anthropic' => new AnthropicProvider($apiKey),
+            'mistral' => new MistralProvider($apiKey),
+            'gemini' => new GeminiProvider($apiKey),
+            'deepseek' => new DeepSeekProvider($apiKey),
+            default => throw new \InvalidArgumentException("Unknown provider: {$provider}")
+        };
+    }
+
+    /**
+     * Get list of supported providers
+     *
+     * @return array
+     */
+    public static function getSupportedProviders(): array
+    {
+        return [
+            'openai',
+            'anthropic',
+            'mistral',
+            'gemini',
+            'deepseek',
+        ];
+    }
+
+    /**
+     * Check if a provider is supported
+     *
+     * @param string $provider
+     * @return bool
+     */
+    public static function isSupported(string $provider): bool
+    {
+        return in_array(strtolower($provider), self::getSupportedProviders());
+    }
+}