graph, node: Warn when running a debug build

Prefix every log line with [DEBUG-BUILD] and emit a startup warning
when graph-node is compiled without --release, so operators are not
silently running a degraded build in production.

Author: dimitrovmaksim

graph/src/log/mod.rs

@@ -97,6 +97,9 @@ where
 
     fn format_custom(&self, record: &Record, values: &OwnedKVList) -> io::Result<()> {
         self.decorator.with_record(record, values, |mut decorator| {
+            #[cfg(debug_assertions)]
+            write!(decorator, "[DEBUG-BUILD] ")?;
+
             decorator.start_timestamp()?;
             formatted_timestamp_local(&mut decorator)?;
             decorator.start_whitespace()?;

node/src/launcher.rs

@@ -413,6 +413,13 @@ pub async fn run(
         render_testament!(TESTAMENT)
     );
 
+    #[cfg(debug_assertions)]
+    warn!(
+        logger,
+        "This is a DEBUG build — performance is severely degraded. \
+        Use `cargo build --release` for production deployments."
+    );
+
     if !graph_server_index_node::PoiProtection::from_env(&ENV_VARS).is_active() {
         warn!(
             logger,