Remove deprecated Flash preview and legacy MTP

src/server.rs

@@ -546,7 +546,7 @@ fn model_json(id: &str, model: ModelChoice, context: i32, default_tokens: i32) -
 
 fn model_alias(id: &str) -> Option<ModelChoice> {
     match id {
-        "deepseek-chat" | "deepseek-reasoner" => Some(ModelChoice::DeepSeekV4Flash),
+        "deepseek-chat" | "deepseek-reasoner" => Some(ModelChoice::DeepSeekV4Flash0731),
         "glm-5.2-chat"
         | "glm-5.2-no-think"
         | "glm-5.2-nothink"
@@ -929,7 +929,7 @@ mod tests {
         let request = ResponseOptions {
             protocol: Protocol::Chat,
             reasoning_summary: false,
-            model_id: "deepseek-v4-flash".into(),
+            model_id: "deepseek-v4-flash-0731".into(),
             stream: true,
             include_usage: false,
             has_tools: true,
@@ -1002,9 +1002,17 @@ mod tests {
 
     #[test]
     fn model_metadata_uses_the_requested_alias_and_default_token_limit() {
+        assert_eq!(
+            model_alias("deepseek-chat"),
+            Some(ModelChoice::DeepSeekV4Flash0731)
+        );
+        assert_eq!(
+            model_alias("deepseek-reasoner"),
+            Some(ModelChoice::DeepSeekV4Flash0731)
+        );
         let model = model_json(
             "deepseek-reasoner",
-            ModelChoice::DeepSeekV4Flash,
+            ModelChoice::DeepSeekV4Flash0731,
             32_768,
             50_000,
         );