feat(openai): add custom model info configuration

Adds support for configuring custom OpenAI-compatible model capabilities and pricing, including:

Max output tokens
Context window size
Image/computer use support
Input/output token pricing
Cache read/write pricing

src/api/providers/openai.ts

@@ -108,7 +108,7 @@ export class OpenAiHandler implements ApiHandler, SingleCompletionHandler {
 	getModel(): { id: string; info: ModelInfo } {
 		return {
 			id: this.options.openAiModelId ?? "",
-			info: openAiModelInfoSaneDefaults,
+			info: this.options.openAiCusModelInfo ?? openAiModelInfoSaneDefaults,
 		}
 	}