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/Models/LlmRequest.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+
+class LlmRequest extends Model
+{
+    protected $fillable = [
+        'user_id',
+        'provider',
+        'model',
+        'request_payload',
+        'response_payload',
+        'prompt_tokens',
+        'completion_tokens',
+        'total_tokens',
+        'response_time_ms',
+        'prompt_cost',
+        'completion_cost',
+        'total_cost',
+        'status',
+        'error_message',
+        'http_status',
+        'ip_address',
+        'user_agent',
+        'request_id',
+    ];
+
+    protected $casts = [
+        'request_payload' => 'array',
+        'response_payload' => 'array',
+        'prompt_tokens' => 'integer',
+        'completion_tokens' => 'integer',
+        'total_tokens' => 'integer',
+        'response_time_ms' => 'integer',
+        'prompt_cost' => 'decimal:6',
+        'completion_cost' => 'decimal:6',
+        'total_cost' => 'decimal:6',
+        'http_status' => 'integer',
+    ];
+
+    public function user(): BelongsTo
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function isSuccess(): bool
+    {
+        return $this->status === 'success';
+    }
+
+    public function isFailed(): bool
+    {
+        return $this->status === 'failed';
+    }
+}