[smg][mesh] extract mesh to mesh crate to reduce compile time (#17907)

sgl-model-gateway/build.rs

@@ -12,7 +12,6 @@ macro_rules! set_env {
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Rebuild triggers
-    println!("cargo:rerun-if-changed=src/mesh/proto/gossip.proto");
     println!("cargo:rerun-if-changed=src/proto/sglang_scheduler.proto");
     println!("cargo:rerun-if-changed=src/proto/vllm_engine.proto");
     println!("cargo:rerun-if-changed=Cargo.toml");
@@ -31,13 +30,6 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             &["src/proto"],
         )?;
 
-    // Compile gossip protobuf files
-    tonic_prost_build::configure()
-        // Generate both client and server code
-        .build_server(true)
-        .build_client(true)
-        .compile_protos(&["src/mesh/proto/gossip.proto"], &["src/mesh/proto"])?;
-
     // Set version info environment variables
     let version = read_cargo_version().unwrap_or_else(|_| DEFAULT_VERSION.to_string());
     let target = std::env::var("TARGET").unwrap_or_else(|_| get_rustc_host().unwrap_or_default());