chore(params): warn at runtime when --limitGenomeGenerateRAM is set

Accepting the flag silently could mislead a user who passes a non-default
cap into thinking rustar enforces it. Emit a warning whenever the value
differs from STAR's default so the user knows the cap isn't applied.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: pinin4fjords

src/lib.rs

@@ -50,6 +50,13 @@ fn genome_generate(params: &Parameters) -> anyhow::Result<()> {
             .collect::<Vec<_>>()
     );
 
+    if params.limit_genome_generate_ram != 31_000_000_000 {
+        log::warn!(
+            "--limitGenomeGenerateRAM {} accepted but not enforced; rustar manages genome-generation memory independently",
+            params.limit_genome_generate_ram
+        );
+    }
+
     info!("Building genome index...");
     let index = GenomeIndex::build(params)?;