Feature Request: Add NVIDIA NIM and OpenAI-Compatible API support for image generation [ENHANCEMENT]

[devpkr1]

Problem (one or two sentences)

Users are locked into using a single third-party provider for the experimental image generation feature, preventing them from using their existing API keys or accounts with other platforms.

Context (who is affected and when)

This affects any user trying to test or use the experimental image generation feature who prefers to use NVIDIA NIM, dedicated OpenAI-compatible endpoints, or local self-hosted models.

Desired behavior (conceptual, not technical)

Users should be able to choose their preferred image generation provider from a settings menu. Selecting a provider like NVIDIA NIM or a custom OpenAI-compatible endpoint should open up fields to input that specific platform's API key and base URL.

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact