Validate bulk binary sizes as integral metadata

Reject boolean and floating-point values for int64 bulk binary sizes instead of
silently converting them with int(). Keep integer strings accepted for existing
NVBench JSON compatibility, and add regression coverage for valid and malformed
size payloads.

python/scripts/nvbench_compare.py

@@ -845,6 +845,16 @@ def extract_binary_filename(summary):
 
 def extract_binary_size(summary):
     value = extract_summary_data_value(summary, "size", "int64")
+    if isinstance(value, bool):
+        raise ValueError(
+            f"summary {summary.get('tag', '<unknown>')!r} field 'size' "
+            f"value {value!r} is not an int64"
+        )
+    if isinstance(value, float):
+        raise ValueError(
+            f"summary {summary.get('tag', '<unknown>')!r} field 'size' "
+            f"value {value!r} is not an int64"
+        )
     try:
         return int(value)
     except (TypeError, ValueError) as exc: