Add more open source image generation and vision models to LMArena

[SuperPat45]

trafficstars

Interested into comparing these open source models who are missing to LMArena:

• Flux.1 schnell, (as dev version is not usable commercially)
• Lumina Image 2.0,
• DeepSeek Janus Pro models.

Also, Gemma 3 and mistral small 3.2 are missing as vision models