add deepseek v4 via openrouter free

internal/handler/openrouter.go

@@ -11,10 +11,11 @@ import (
 var openRouterKey = os.Getenv("OP_Rowproxy_key")
 
 var openRouterModels = map[string]string{
-	"deepseek-r1":       "deepseek/deepseek-r1",
-	"deepseek-v3":       "deepseek/deepseek-v3.2",
-	"deepseek-r1-0528":  "deepseek/deepseek-r1-0528",
-	"deepseek-v3-turbo": "deepseek/deepseek-v3.1-terminus",
+	"deepseek-r1":        "deepseek/deepseek-r1:free",
+	"deepseek-v3":        "deepseek/deepseek-v3.2:free",
+	"deepseek-r1-0528":   "deepseek/deepseek-r1-0528:free",
+	"deepseek-v4-flash":  "deepseek/deepseek-v4-flash:free",
+	"deepseek-v4-pro":    "deepseek/deepseek-v4-pro:free",
 }
 
 func IsOpenRouterModel(model string) bool {