fix: resolve retired/preview gemini model routing and test configuration errors

internal/server/providers_admin.go

@@ -226,11 +226,11 @@ func (s *Server) handleTestProvider(c *gin.Context) {
 
 	// Adjust model for non-openai providers
 	if name == "gemini" {
-		testReq.Model = "gemini-2.0-flash"
+		testReq.Model = "gemini-2.5-flash"
 	} else if name == "deepseek" {
 		testReq.Model = "deepseek-chat"
 	} else if name == "moonshot" {
-		testReq.Model = "kimi-k2.5"
+		testReq.Model = "kimi-k2.7-code"
 	} else if name == "grok" {
 		testReq.Model = "grok-4-1-fast-non-reasoning"
 	} else if name == "xiaomi" {