hotfix: Complete API coverage with missing @method annotations

- Add 22+ missing @method annotations for complete Discogs API coverage
- Fix broken collectionFolder() method (was mapped to non-existent endpoint)
- Replace with collectionFolderGet() mapping to collection.folder.get
- Update documentation to reflect correct method names
- Maintain logical grouping of marketplace methods (listings → fees → stats → orders)

This hotfix addresses incomplete PHPDoc coverage discovered in v3.0.0
and fixes a broken method that was causing runtime errors.

Breaking Change: collectionFolder() → collectionFolderGet()
This is documented as a bugfix since the original method was non-functional.

Author: calliostro

CHANGELOG.md

@@ -20,6 +20,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Incorrect legacy method mappings in UPGRADE guide
 - Missing PHPDoc annotations causing incomplete IDE support
 - PSR-12 compliance issues in documentation examples
+- Broken `collectionFolder()` method annotation (replaced with working `collectionFolderGet()`)
 
 ### Documentation
 

README.md

@@ -264,7 +264,7 @@ For complete API documentation including all available parameters, visit the [Di
 
 - `collectionFolders($params)` – Get user's collection folders
 - `collectionItems($params)` – Get collection items by folder
-- `collectionFolder($params)` – Get specific collection folder
+- `collectionFolderGet($params)` – Get specific collection folder
 
 #### User Methods