Remove deprecated Flash preview and legacy MTP

scripts/endpoint_parity.py

@@ -16,7 +16,7 @@ cases = [
         "chat",
         "/v1/chat/completions",
         {
-            "model": "deepseek-v4-flash",
+            "model": "deepseek-v4-flash-0731",
             "messages": [
                 {
                     "role": "user",
@@ -42,7 +42,7 @@ cases = [
         "anthropic",
         "/v1/messages",
         {
-            "model": "deepseek-v4-flash",
+            "model": "deepseek-v4-flash-0731",
             "messages": [
                 {
                     "role": "user",
@@ -65,7 +65,7 @@ cases = [
         "responses",
         "/v1/responses",
         {
-            "model": "deepseek-v4-flash",
+            "model": "deepseek-v4-flash-0731",
             "input": "Call echo with text hi. Do not answer normally.",
             "tools": [
                 {