fix: address Octocode review — move size check, add tests for all 3 fixes

- Move file size check before try block so IOError propagates cleanly
  (not caught by the except OSError handler below it)
- Wrap os.path.getsize in its own try/except to preserve existing
  test_normalize_io_error behavior on missing files
- Add test_normalize_rejects_large_file (mocked getsize)
- Add test_null_arguments_does_not_hang (#394)
- Add test_cmd_repair_trailing_slash_does_not_recurse (#395)

532 tests pass locally, 0 regressions.

mempalace/normalize.py

@@ -27,8 +27,11 @@ def normalize(filepath: str) -> str:
     """
     try:
         file_size = os.path.getsize(filepath)
-        if file_size > 500 * 1024 * 1024:  # 500 MB safety limit
-            raise IOError(f"File too large ({file_size // (1024*1024)} MB): {filepath}")
+    except OSError as e:
+        raise IOError(f"Could not read {filepath}: {e}")
+    if file_size > 500 * 1024 * 1024:  # 500 MB safety limit
+        raise IOError(f"File too large ({file_size // (1024*1024)} MB): {filepath}")
+    try:
         with open(filepath, "r", encoding="utf-8", errors="replace") as f:
             content = f.read()
     except OSError as e: