fix: expand ~ in split command directory argument (#361)

Path("~/foo") does not expand tilde on its own, causing
`mempalace split ~/some/dir` to silently find no files.

Fix by calling .expanduser().resolve() in both places the
path is constructed: cmd_split in cli.py (defensive, at the
CLI boundary) and main() in split_mega_files.py (the root cause).

Co-authored-by: Brooke Whatnall <brookewhatnall@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

mempalace/cli.py

@@ -134,7 +134,8 @@ def cmd_split(args):
     import sys
 
     # Rebuild argv for split_mega_files argparse
-    argv = ["--source", args.dir]
+    # Expand ~ and resolve to absolute path so split_mega_files sees a real path
+    argv = ["--source", str(Path(args.dir).expanduser().resolve())]
     if args.output_dir:
         argv += ["--output-dir", args.output_dir]
     if args.dry_run: