Fix API controllers to use correct database column names

- Fix model_pricing table references (model_id -> model, display_name -> model)
- Fix price columns (output_price_per_1k -> output_price_per_million)
- Add price conversion (per_million / 1000 = per_1k) in all API responses
- Add whereNotNull('model') filters to exclude invalid entries
- Add getModelDisplayName() helper method to all controllers
- Fix AccountController to use gateway_users budget fields directly
- Remove Budget model dependencies from AccountController
- Add custom Scramble server URL configuration for API docs
- Create ScrambleServiceProvider to set correct /api prefix
- Add migration to rename user_id to gateway_user_id in llm_requests
- Add custom ApiGuard for gateway_users authentication
- Update all API controllers: AccountController, ModelController, PricingController, ProviderController

All API endpoints now working correctly:
- GET /api/account
- GET /api/models
- GET /api/pricing
- GET /api/providers/{provider}

laravel-app/config/scramble.php

@@ -29,7 +29,77 @@ return [
         /*
          * Description rendered on the home page of the API documentation (`/docs/api`).
          */
-        'description' => '',
+        'description' => '
+# Laravel LLM Gateway API
+
+Multi-provider LLM Gateway supporting OpenAI, Anthropic, Google Gemini, DeepSeek, and Mistral AI.
+
+## Authentication
+
+All API requests require authentication via API key in the **Authorization** header:
+
+```
+Authorization: Bearer {your_api_key_here}
+```
+
+Gateway users receive API keys from the admin interface. Each key is linked to a specific gateway user with their budget limits, rate limits, and provider credentials.
+
+## Providers
+
+The gateway supports the following LLM providers:
+
+* **openai** - OpenAI models (GPT-4, GPT-3.5-turbo, etc.)
+* **anthropic** - Anthropic Claude models (Claude 3, Claude Sonnet, etc.)
+* **gemini** - Google Gemini models (Gemini Pro, etc.)
+* **deepseek** - DeepSeek models (DeepSeek Chat, DeepSeek Coder)
+* **mistral** - Mistral AI models (Mistral Large, Mistral Medium, etc.)
+
+## Rate Limits
+
+Each gateway user has configurable rate limits (default: 60 requests/hour). Rate limit information is returned in error responses when exceeded:
+
+```json
+{
+  "error": "Rate limit exceeded",
+  "limit": 60,
+  "reset_at": "2024-01-15T14:30:00Z"
+}
+```
+
+## Budgets
+
+Monthly budget limits are enforced per gateway user. Costs are calculated based on token usage and provider-specific pricing. When the budget is exceeded, requests return:
+
+```json
+{
+  "error": "Budget exceeded",
+  "current": 150.50,
+  "limit": 100.00
+}
+```
+
+## Error Handling
+
+The API returns structured error responses:
+
+* **400** Bad Request - Invalid parameters
+* **401** Unauthorized - Invalid or missing API key
+* **403** Forbidden - Budget exceeded
+* **404** Not Found - User blocked
+* **429** Too Many Requests - Rate limit exceeded
+* **500** Internal Server Error - Unexpected error
+
+## Cost Tracking
+
+All requests are logged with:
+* Model used
+* Input/output tokens
+* Calculated cost
+* Provider response time
+* Error details (if any)
+
+Administrators can view detailed usage analytics in the admin interface.
+        ',
     ],
 
     /*
@@ -89,7 +159,9 @@ return [
      * ],
      * ```
      */
-    'servers' => null,
+    'servers' => [
+        'Local' => 'http://localhost/api',
+    ],
 
     /**
      * Determines how Scramble stores the descriptions of enum cases.