feat(spur-cli): support --nodefile and file-path detection in -w/--nodelist

[shiv-tyagi]

Problem

Slurm interprets a -w/--nodelist value containing / as a filename, reading node names from that file (one per line or comma-separated). It also provides -F/--nodefile as an explicit alternative. Spur treats the value as a literal string in all cases.

Slurm also supports node1*2 repetition syntax for --distribution=arbitrary. Spur does not.

Expected behavior

• -w /path/to/nodes.txt reads node names from the file
• -F/--nodefile accepted as an alias
• node1*2 expands to node1,node1 (only relevant with --distribution=arbitrary)

Notes

Both features are rarely used in practice. The file-path detection is the more useful of the two. The repetition syntax is only meaningful with distribution modes Spur doesn't yet implement.

Acceptance criteria

• -w /tmp/nodes.txt reads the file and expands to node names
• -F /tmp/nodes.txt works identically
• node1*2 expands correctly (if distribution=arbitrary is supported)