docs(benchmarks): record verified django compare run

[mstykow]

Summary

• Record the verified django/django compare-outputs --profile common run in docs/BENCHMARKS.md, including the pinned commit, timing data, and end-state Provenant advantages.

Scope and exclusions

• Included: the Django benchmark row in docs/BENCHMARKS.md.
• Explicit exclusions: no scorecard wording changes, parser logic changes, or fixture updates.

Follow-up work

• Created or intentionally deferred: continue Python-family verification with pandas-dev/pandas in a separate follow-up branch.