Restore Node heap to 6 GB now that swap prevents OOM kills

With 14 GB swap as safety net, the 6 GB heap allows V8 to GC less
aggressively, improving build performance. Brief memory peaks above
7 GB will use swap instead of crashing.

Author: Miggets7

.github/workflows/ci_cd.yml

@@ -15,8 +15,8 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  # Hosted GitHub runners have 7 GB of memory available, reserve ~3 GB for Rspack native memory and OS
-  NODE_OPTIONS: --max-old-space-size=4096
+  # Hosted GitHub runners have 7 GB of memory available, swap handles brief peaks above this
+  NODE_OPTIONS: --max-old-space-size=6144
 
 jobs:
   build: