3.0.0-RC4

chore(form): allow horde-installer-plugin in composer config
feat(form): document AssetManager page output integration
feat(form): Add support for PSR-7 file upload to V3 FileVariable and ImageVariable
chore: mark global statements for DI refactoring
refactor(image): Improve _getUpload, remove getUploadedFileType method - Separate upload handling from try/catch: file-not-uploaded logic - Build $img as a local array and assign to $this->_img at the end, rather than mutating $this->_img piecemeal throughout the method - Remove getUploadedFileType static method, inline/improve its logic - Related code improvements
refactor: use PSR-4 version of nls
chore: Update workflow dependency
Refactor validation logic for form variables