Enhance file upload functionality and update .gitignore

[rhythmatician]

Improve file upload capabilities to support multipart/form-data across multiple APIs. Update .gitignore to exclude temporary and backup files. Fix handling of empty response content in specific upload functions.

[Copilot]

Pull request overview

This PR updates the Qualer SDK’s upload endpoints to correctly send multipart/form-data payloads via httpx, adds tests to validate request construction, and refreshes API docs and repo ignore patterns accordingly.

Changes:

• Add files: List[File] support to multiple upload endpoints and construct httpx files= payloads.
• Add unit + integration tests covering multipart request construction and end-to-end upload behavior.
• Update markdown API docs and extend .gitignore for temp/backup files.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/qualer_sdk/api/service_order_documents/upload_documents_post_2.py	Adds multipart files= support and adjusts empty-body JSON parsing.
src/qualer_sdk/api/service_order_item_documents/upload_documents_post_3.py	Adds multipart files= support and adjusts empty-body JSON parsing.
src/qualer_sdk/api/asset_service_records/upload_documents.py	Adds multipart files= support and adjusts empty-body JSON parsing.
src/qualer_sdk/api/service_order_items/upload_work_item_images.py	Adds multipart files= support and handles 204 responses with empty bodies.
tests/unit/test_upload_endpoints.py	New unit tests validating _get_kwargs() includes correct files tuples and avoids manual Content-Type.
tests/integration/test_upload_documents.py	New integration tests performing real uploads (VCR-marked) to validate end-to-end multipart behavior.
docs/ServiceOrderDocumentsApi.md	Updates signature/examples and indicates multipart/form-data.
docs/ServiceOrderItemDocumentsApi.md	Updates signature/examples and indicates multipart/form-data.
docs/ServiceOrderItemsApi.md	Updates signature/examples and indicates multipart/form-data.
docs/AssetServiceRecordsApi.md	Updates signature/examples and indicates multipart/form-data.
.gitignore	Ignores temp and .bak files.