Add Mistral Medium 3 support

[KanTakahiro]

Mistral announced "Mistral Medium 3" model and said the new Mistral Medium model will take place current Mistral Large 2 model.
Medium is the new large
Please add Mistral Medium 3 support for a better performance/cost balance than Mistral Large 2.

Just add a item in src/shared/api.ts

	"mistral-medium-latest": {
		maxTokens: 131_000,
		contextWindow: 131_000,
		supportsImages: True,
		supportsPromptCache: false,
		inputPrice: 0.4,
		outputPrice: 2.0,
	},

[KanTakahiro]

Just open a PR request for this issue: #4588