fix(api): update cacheReadsPrice for OpenAI GPT-4.1 models (#2887)

Set correct cacheReadsPrice (cached input price) for gpt-4.1, gpt-4.1 mini, and gpt-4.1 nano based on official OpenAI pricing. No changes to cacheWritesPrice as per current OpenAI documentation. This ensures prompt caching costs are accurately reflected for these models in cost calculations.

Author: monotykamary

src/shared/api.ts

@@ -754,6 +754,7 @@ export const openAiNativeModels = {
 		supportsPromptCache: true,
 		inputPrice: 2,
 		outputPrice: 8,
+		cacheReadsPrice: 0.5,
 	},
 	"gpt-4.1-mini": {
 		maxTokens: 32_768,
@@ -762,6 +763,7 @@ export const openAiNativeModels = {
 		supportsPromptCache: true,
 		inputPrice: 0.4,
 		outputPrice: 1.6,
+		cacheReadsPrice: 0.1,
 	},
 	"gpt-4.1-nano": {
 		maxTokens: 32_768,
@@ -770,6 +772,7 @@ export const openAiNativeModels = {
 		supportsPromptCache: true,
 		inputPrice: 0.1,
 		outputPrice: 0.4,
+		cacheReadsPrice: 0.025,
 	},
 	"o3-mini": {
 		maxTokens: 100_000,