Harden nvbench-compare parsing and plot tests

Reject boolean summary float payloads instead of coercing them to 1.0/0.0,
while keeping numeric strings accepted for NVBench JSON compatibility.

Add regression coverage for generated bulk-debug Python filenames that require
escaping, and strengthen the plot-along test to assert log-log axes and
confidence-band rendering.

python/scripts/nvbench_compare.py

@@ -828,6 +828,8 @@ def extract_summary_value(summary):
 def normalize_float_value(value, *, null_value=None):
     if value is None:
         return null_value
+    if isinstance(value, bool):
+        return null_value
     return float(value)