fix: add timeouts to HTTP client to prevent freezing (#675)

* fix: add timeouts to HTTP client to prevent freezing

When running Helios for extended periods, the HTTP client could hang
indefinitely on network requests if the beacon node becomes unresponsive
or network issues occur. This would cause the consensus sync loop to
freeze, preventing the client from following the chain.

This fix adds:
- 30 second timeout for individual requests
- 10 second connection timeout
- 60 second idle connection cleanup

These timeouts ensure that network issues or unresponsive beacon nodes
won't cause Helios to freeze permanently, allowing it to recover and
continue syncing.

* fix: ensure WASM compatibility for HTTP client timeouts

- Use conditional compilation to only apply timeout settings on non-WASM targets
- WASM builds use default reqwest client without timeouts (not supported in WASM)
- Conditionally import Duration only for non-WASM builds to avoid warnings

Author: ncitron

ethereum/src/rpc/http_rpc.rs

@@ -1,4 +1,6 @@
 use std::cmp;
+#[cfg(not(target_arch = "wasm32"))]
+use std::time::Duration;
 
 use alloy::primitives::B256;
 use async_trait::async_trait;
@@ -68,8 +70,19 @@ impl HttpRpc {
 #[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
 impl<S: ConsensusSpec> ConsensusRpc<S> for HttpRpc {
     fn new(rpc: &str) -> Self {
+        #[cfg(not(target_arch = "wasm32"))]
+        let client = reqwest::Client::builder()
+            .timeout(Duration::from_secs(30)) // Add request timeout
+            .connect_timeout(Duration::from_secs(10)) // Add connection timeout
+            .pool_idle_timeout(Duration::from_secs(60)) // Clean up idle connections
+            .build()
+            .unwrap_or_else(|_| reqwest::Client::new());
+
+        #[cfg(target_arch = "wasm32")]
+        let client = reqwest::Client::new();
+
         HttpRpc {
-            client: reqwest::Client::new(),
+            client,
             rpc: rpc.trim_end_matches('/').to_string(),
         }
     }