Update deepseek-chat context window size 64k -> 128k

deepseek-chat points at DeepSeek-V3
which has context window 128k,
see https://github.com/deepseek-ai/DeepSeek-V3
Though the change is not yet reflected in DeepSeek API docs,
where it erroneously shows 64k

Author: NikolayXHD

src/shared/api.ts

@@ -799,7 +799,7 @@ export const deepSeekDefaultModelId: DeepSeekModelId = "deepseek-chat"
 export const deepSeekModels = {
 	"deepseek-chat": {
 		maxTokens: 8192,
-		contextWindow: 64_000,
+		contextWindow: 128_000,
 		supportsImages: false,
 		supportsPromptCache: true,
 		inputPrice: 0.27, // $0.27 per million tokens (cache miss)