Allow PNG/Image uploads for AI Invoice Analysis

[google-labs-jules]

Allows PNG and other image formats to be processed by the AI invoice analysis by sending them as image_url content instead of file uploads.

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PR created automatically by Jules for task 1418713396572574347 started by @kellertobias

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Note

OpenAI requests now embed image attachments as data-URI image_url and upload non-image files, with tests covering both paths.

• Backend:
  • LLMService (src/backend/services/llm.service.ts):
    • OpenAI: detect attachment type; images are sent as image_url (data URI), non-images are uploaded via files.create (using toFile) and referenced as file with file_id.
    • Import toFile from openai to support file uploads.
• Tests:
  • src/backend/services/llm.service.spec.ts:
    • Add test verifying images are sent via image_url and no file upload occurs.
    • Add test verifying PDFs trigger file upload and are referenced by file_id.

^{Written by Cursor Bugbot for commit 37d5521. This will update automatically on new commits. Configure here.}

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