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/Providers/AnthropicProvider.php

@@ -0,0 +1,113 @@
+<?php
+
+namespace App\Services\LLM\Providers;
+
+use App\Models\ModelPricing;
+use Illuminate\Support\Facades\Cache;
+
+class AnthropicProvider extends AbstractProvider
+{
+    protected string $baseUrl = 'https://api.anthropic.com/v1';
+    private string $apiVersion = '2023-06-01';
+
+    protected function buildRequest(array $messages, array $options): array
+    {
+        // Anthropic requires system message separate
+        $systemMessage = null;
+        $formattedMessages = [];
+
+        foreach ($messages as $message) {
+            if ($message['role'] === 'system') {
+                $systemMessage = $message['content'];
+            } else {
+                $formattedMessages[] = $message;
+            }
+        }
+
+        $request = array_filter([
+            'model' => $options['model'] ?? 'claude-sonnet-4',
+            'max_tokens' => $options['max_tokens'] ?? 4096,
+            'messages' => $formattedMessages,
+            'system' => $systemMessage,
+            'temperature' => $options['temperature'] ?? null,
+            'top_p' => $options['top_p'] ?? null,
+            'stop_sequences' => $options['stop'] ?? null,
+        ], fn($value) => $value !== null);
+
+        return $request;
+    }
+
+    protected function getAuthHeaders(): array
+    {
+        return [
+            'x-api-key' => $this->apiKey,
+            'anthropic-version' => $this->apiVersion,
+            'Content-Type' => 'application/json',
+        ];
+    }
+
+    public function chatCompletion(array $messages, array $options = []): array
+    {
+        $data = $this->buildRequest($messages, $options);
+        return $this->makeRequest('/messages', $data);
+    }
+
+    public function normalizeResponse(array $response): array
+    {
+        $content = '';
+        if (isset($response['content']) && is_array($response['content'])) {
+            foreach ($response['content'] as $block) {
+                if ($block['type'] === 'text') {
+                    $content .= $block['text'];
+                }
+            }
+        }
+
+        return [
+            'id' => $response['id'] ?? null,
+            'model' => $response['model'] ?? null,
+            'content' => $content,
+            'role' => $response['role'] ?? 'assistant',
+            'finish_reason' => $response['stop_reason'] ?? null,
+            'usage' => [
+                'prompt_tokens' => $response['usage']['input_tokens'] ?? 0,
+                'completion_tokens' => $response['usage']['output_tokens'] ?? 0,
+                'total_tokens' => ($response['usage']['input_tokens'] ?? 0) + ($response['usage']['output_tokens'] ?? 0),
+            ],
+            'raw_response' => $response,
+        ];
+    }
+
+    public function calculateCost(int $promptTokens, int $completionTokens, string $model): float
+    {
+        $cacheKey = "pricing:anthropic:{$model}";
+
+        $pricing = Cache::remember($cacheKey, 3600, function () use ($model) {
+            return ModelPricing::where('provider', 'anthropic')
+                ->where('model', $model)
+                ->where('is_active', true)
+                ->first();
+        });
+
+        if (!$pricing) {
+            return 0.0;
+        }
+
+        $promptCost = ($promptTokens / 1_000_000) * $pricing->input_price_per_million;
+        $completionCost = ($completionTokens / 1_000_000) * $pricing->output_price_per_million;
+
+        return round($promptCost + $completionCost, 6);
+    }
+
+    public function getSupportedModels(): array
+    {
+        return [
+            'claude-opus-4',
+            'claude-sonnet-4',
+            'claude-haiku-4',
+            'claude-3-opus',
+            'claude-3-sonnet',
+            'claude-3-haiku',
+        ];
+    }
+}