Fix test profile memory configuration for xengsort

Resolved out-of-memory errors in XENGSORT_CLASSIFY by:

1. Made xengsort index size configurable via ext.args
   - Updated xengsort_index.nf to accept custom args
   - Default remains -n 4500000000 -k 25 for production use

2. Optimized test profile for small test data
   - Reduced index size to -n 100000000 (22x smaller) for test data
   - Increased XENGSORT_CLASSIFY memory from 4GB to 8GB
   - Smaller index loads faster and uses less RAM

This allows the test profile to run successfully with tiny test files
while maintaining production settings for real data.

Author: Seqera AI

modules/xengsort_index.nf

@@ -10,13 +10,13 @@ process XENGSORT_INDEX {
     path "xengsort_index.*", emit: index_files
 
     script:
+    def args = task.ext.args ?: '-n 4500000000 -k 25'
     """
     xengsort index \\
         --index xengsort_index \\
         --host ${mouse_fasta} \\
         --graft ${human_fasta} \\
-        -n 4500000000 \\
-        -k 25
+        ${args}
      """
 
     // Add a stub block for minimal test

nextflow.config

@@ -39,13 +39,15 @@ profiles {
 
             // Specific configuration for memory-intensive processes
             withName: 'XENGSORT_CLASSIFY' {
-                memory = '4.GB'
+                memory = '8.GB'
                 cpus = 2
             }
 
             withName: 'XENGSORT_INDEX' {
                 memory = '2.GB'
                 cpus = 2
+                // Use much smaller index for test data to reduce memory requirements
+                ext.args = '-n 100000000 -k 25'
             }
         }
         params {