feat: extend hotpath coverage across crates (#5505)

Add opt-in hotpath feature surfaces to every workspace crate and wire the root rustfs feature passthrough for function, allocation, and CPU profiling.

Add a focused set of function-level measurements for scanner, heal, lock, target replay, IAM, KMS, Keystone, trusted proxy, and capacity paths without adding request-scoped primitive wrappers.

Co-authored-by: heihutu <heihutu@gmail.com>

crates/scanner/src/scanner.rs

@@ -2531,6 +2531,7 @@ where
 }
 
 #[instrument(skip_all)]
+#[hotpath::measure]
 async fn run_data_scanner_cycle(
     ctx: &CancellationToken,
     storeapi: &Arc<ECStore>,