Reads b3_policy_comparison.json (produced by b3_analyze.sh) and emits
a markdown report with three tables: headline latency + APC,
mechanism indices (interference / hotspot / reuse), and slow-request
cause breakdown. Rows for policies not yet present in the sweep are
left as "pending" so the same renderer can be re-invoked as each
policy finishes, producing an evolving report rather than waiting
for the full sweep.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>