docs: update ShopRenter API resources to focus on GET methods only #58

- Added clear warning about read-only integration at the top
- Updated all three extend resources (order, customer, product) to show only GET endpoints
- Removed all POST, PUT, DELETE operations from documentation
- Emphasized read-only nature in integration notes
- Updated use cases and operations to reflect read-only access
- Changed language from "create/update/manage" to "retrieve/access/read"

This reflects the actual usage where we only retrieve data without modifying anything on ShopRenter stores.

docs/shoprenter_api_resources.md

@@ -4,6 +4,8 @@
 
 This document covers the ShopRenter Developer API resources with focus on authentication and extended resources for orders, customers, and products.
 
+**⚠️ Read-Only Integration**: This integration only uses GET methods to retrieve data. We do not create, update, or delete any data on ShopRenter stores.
+
 ## Authentication
 
 The ShopRenter API uses OAuth 2.0 authentication. Based on the existing implementation in this project:
@@ -90,19 +92,22 @@ Specifies the payment processor or method used. Supported values include:
 - `mbh_credit` - MBH Bank credit
 - `otp_szep_card` - OTP SZÉP card (Hungarian benefit card)
 
-### API Endpoints
+### API Endpoints (Read-Only)
 
-Standard REST operations for order extend data:
-- **GET** `/orderExtends` - List order extends
-- **GET** `/orderExtends/{id}` - Get specific order extend
-- **POST** `/orderExtends` - Create order extend
-- **PUT** `/orderExtends/{id}` - Update order extend
-- **DELETE** `/orderExtends/{id}` - Delete order extend
+**Note**: This integration uses read-only access to order extend data.
+
+Available GET endpoints:
+- **GET** `/orderExtends` - List all order extends
+  - Supports pagination and filtering
+  - Returns array of order extend objects
+- **GET** `/orderExtends/{id}` - Get specific order extend by ID
+  - Returns single order extend object
+  - Includes full shipping and payment method details
 
 ### Integration Notes
-- Order Extend sits between Order Credit Card and Order History in the API workflow
-- Used to capture detailed shipping and payment metadata
-- Essential for logistics integration and payment reconciliation
+- **Read-only access**: We only retrieve data, no modifications
+- Order Extend provides detailed shipping and payment metadata
+- Essential for understanding logistics providers and payment methods used
 
 ## Customer Extend Resource
 
@@ -116,20 +121,23 @@ Extends basic customer information with supplementary fields for enhanced custom
 - Additional metadata storage
 - Integration with Customer Resource and Customer Group Resource
 
-### API Endpoints
+### API Endpoints (Read-Only)
 
-Standard REST operations for customer extend data:
-- **GET** `/customerExtends` - List customer extends
-- **GET** `/customerExtends/{id}` - Get specific customer extend
-- **POST** `/customerExtends` - Create customer extend
-- **PUT** `/customerExtends/{id}` - Update customer extend
-- **DELETE** `/customerExtends/{id}` - Delete customer extend
+**Note**: This integration uses read-only access to customer extend data.
+
+Available GET endpoints:
+- **GET** `/customerExtends` - List all customer extends
+  - Supports pagination and filtering
+  - Returns array of customer extend objects
+- **GET** `/customerExtends/{id}` - Get specific customer extend by ID
+  - Returns single customer extend object
+  - Includes all extended customer properties
 
 ### Use Cases
-- Storing custom customer attributes
-- Managing extended customer profiles
-- Supporting custom CRM workflows
-- Tracking additional customer preferences
+- Reading custom customer attributes
+- Accessing extended customer profiles
+- Retrieving additional customer metadata
+- Viewing customer preferences and custom fields
 
 ### Related Resources
 - **Customer Resource** - Base customer data
@@ -157,55 +165,51 @@ Extends standard product data with additional attributes, relationships, and met
 - **External Identifiers** - Map to external system IDs
 - **Document Relations** - Link products to related documents
 
-### API Endpoints
+### API Endpoints (Read-Only)
+
+**Note**: This integration uses read-only access to product extend data.
+
+Available GET endpoints:
+- **GET** `/productExtends` - List all product extends
+  - Supports pagination and filtering
+  - Returns array of product extend objects
+- **GET** `/productExtends/{id}` - Get specific product extend by ID
+  - Returns single product extend object
+  - Includes category links, images, attributes, and pricing
 
-Standard REST operations for product extend data:
-- **GET** `/productExtends` - List product extends
-- **GET** `/productExtends/{id}` - Get specific product extend
-- **POST** `/productExtends` - Create product extend
-- **PUT** `/productExtends` - Update product extend
-- **DELETE** `/productExtends/{id}` - Delete product extend
-
-### Common Operations
-
-#### Linking Products with Categories
-```
-POST /productExtends
-{
-  "productId": "123",
-  "categoryIds": ["456", "789"]
-}
-```
-
-#### Attaching Images
-```
-POST /productExtends/{id}/images
-{
-  "imageUrl": "https://...",
-  "sortOrder": 1
-}
-```
-
-#### Managing Special Pricing
-```
-PUT /productExtends/{id}
-{
-  "specialPrice": 99.99,
-  "specialPriceStart": "2024-01-01",
-  "specialPriceEnd": "2024-01-31"
-}
-```
-
-#### Batch Upload
-Use batch operations for importing large product catalogs with extended attributes.
-
-#### Category Assignment with External IDs
-Map products to categories using external system identifiers for seamless integration.
+### Data Available via GET
+
+When reading product extend data, you can access:
+
+#### Category Associations
+- Product-to-category mappings
+- Multiple category assignments per product
+- Category hierarchy information
+
+#### Product Images
+- Image URLs and metadata
+- Sort order for display
+- Primary and additional images
+
+#### Special Pricing
+- Promotional pricing information
+- Special price start and end dates
+- Discount details
+
+#### Extended Attributes
+- Custom product attributes
+- Additional product metadata
+- External system identifiers
+
+#### Product Relationships
+- Related products
+- Product documents
+- Cross-references to other resources
 
 ### Integration Context
-- Sits between Product Document Relation and Product Image resources
-- Works with core Product Resource for complete catalog management
-- Supports complex e-commerce scenarios requiring extended metadata
+- **Read-only access**: We retrieve extended product data without modifications
+- Complements core Product Resource for complete catalog information
+- Provides access to extended metadata for analytics and display purposes
 
 ## Synchronization