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/tests/Unit/Services/AnthropicProviderTest.php

@@ -0,0 +1,144 @@
+<?php
+
+namespace Tests\Unit\Services;
+
+use Tests\TestCase;
+use App\Services\LLM\Providers\AnthropicProvider;
+use App\Models\ModelPricing;
+use Illuminate\Support\Facades\Http;
+use Illuminate\Support\Facades\Cache;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+class AnthropicProviderTest extends TestCase
+{
+    use RefreshDatabase;
+
+    private AnthropicProvider $provider;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->provider = new AnthropicProvider('test-api-key');
+    }
+
+    public function test_builds_request_correctly_with_system_message(): void
+    {
+        $messages = [
+            ['role' => 'system', 'content' => 'You are a helpful assistant'],
+            ['role' => 'user', 'content' => 'Hello']
+        ];
+        
+        $options = [
+            'model' => 'claude-sonnet-4',
+            'temperature' => 0.7,
+            'max_tokens' => 2000
+        ];
+
+        $reflection = new \ReflectionClass($this->provider);
+        $method = $reflection->getMethod('buildRequest');
+        $method->setAccessible(true);
+
+        $result = $method->invoke($this->provider, $messages, $options);
+
+        $this->assertEquals('claude-sonnet-4', $result['model']);
+        $this->assertEquals(0.7, $result['temperature']);
+        $this->assertEquals(2000, $result['max_tokens']);
+        $this->assertEquals('You are a helpful assistant', $result['system']);
+        $this->assertCount(1, $result['messages']); // System message extracted
+        $this->assertEquals('user', $result['messages'][0]['role']);
+    }
+
+    public function test_normalizes_response_correctly(): void
+    {
+        $rawResponse = [
+            'id' => 'msg_123',
+            'model' => 'claude-sonnet-4',
+            'content' => [
+                [
+                    'type' => 'text',
+                    'text' => 'Hello! How can I assist you today?'
+                ]
+            ],
+            'role' => 'assistant',
+            'stop_reason' => 'end_turn',
+            'usage' => [
+                'input_tokens' => 15,
+                'output_tokens' => 25
+            ]
+        ];
+
+        $normalized = $this->provider->normalizeResponse($rawResponse);
+
+        $this->assertEquals('msg_123', $normalized['id']);
+        $this->assertEquals('claude-sonnet-4', $normalized['model']);
+        $this->assertEquals('Hello! How can I assist you today?', $normalized['content']);
+        $this->assertEquals('assistant', $normalized['role']);
+        $this->assertEquals('end_turn', $normalized['finish_reason']);
+        $this->assertEquals(15, $normalized['usage']['prompt_tokens']);
+        $this->assertEquals(25, $normalized['usage']['completion_tokens']);
+        $this->assertEquals(40, $normalized['usage']['total_tokens']);
+    }
+
+    public function test_calculates_cost_correctly(): void
+    {
+        // Create pricing in database
+        ModelPricing::create([
+            'provider' => 'anthropic',
+            'model' => 'claude-sonnet-4',
+            'input_price_per_million' => 3.00,
+            'output_price_per_million' => 15.00,
+            'is_active' => true,
+            'effective_from' => now()
+        ]);
+
+        Cache::flush();
+
+        $cost = $this->provider->calculateCost(1000, 500, 'claude-sonnet-4');
+
+        // Expected: (1000/1M * 3.00) + (500/1M * 15.00) = 0.003 + 0.0075 = 0.0105
+        $this->assertEquals(0.0105, $cost);
+    }
+
+    public function test_handles_api_errors(): void
+    {
+        Http::fake([
+            'https://api.anthropic.com/*' => Http::response(['error' => 'Invalid API key'], 401)
+        ]);
+
+        $this->expectException(\App\Exceptions\ProviderException::class);
+        $this->expectExceptionMessage('Invalid API key');
+
+        $this->provider->chatCompletion([
+            ['role' => 'user', 'content' => 'test']
+        ]);
+    }
+
+    public function test_get_supported_models(): void
+    {
+        $models = $this->provider->getSupportedModels();
+
+        $this->assertIsArray($models);
+        $this->assertContains('claude-opus-4', $models);
+        $this->assertContains('claude-sonnet-4', $models);
+        $this->assertContains('claude-haiku-4', $models);
+    }
+
+    public function test_handles_multiple_content_blocks(): void
+    {
+        $rawResponse = [
+            'id' => 'msg_456',
+            'model' => 'claude-sonnet-4',
+            'content' => [
+                ['type' => 'text', 'text' => 'First part. '],
+                ['type' => 'text', 'text' => 'Second part.']
+            ],
+            'role' => 'assistant',
+            'stop_reason' => 'end_turn',
+            'usage' => ['input_tokens' => 10, 'output_tokens' => 20]
+        ];
+
+        $normalized = $this->provider->normalizeResponse($rawResponse);
+
+        $this->assertEquals('First part. Second part.', $normalized['content']);
+    }
+}