[router][grpc] Restructure modules and code clean up (#12598)

sgl-router/src/tokenizer/chat_template.rs

@@ -18,20 +18,15 @@ use minijinja::{
 use serde_json;
 
 /// Chat template content format
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
 pub enum ChatTemplateContentFormat {
     /// Content is a simple string
+    #[default]
     String,
     /// Content is a list of structured parts (OpenAI format)
     OpenAI,
 }
 
-impl Default for ChatTemplateContentFormat {
-    fn default() -> Self {
-        Self::String
-    }
-}
-
 impl std::fmt::Display for ChatTemplateContentFormat {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {