bench backfill: +1210 Python complexity-class models across 583 projects

Scripted backfill via /tmp/backfill_batch.py. Per defect:
  - Extract first 'Fixes {id}: ...' line from the patch as the bench header,
    keeping the per-defect context in the section title.
  - Write bench-{defect-id}.py modelling O(N*k) list-scan vs O(N+k) set
    membership. Each bench runs at 4 scales (N,k = 100..2000).
  - Regenerate bench/run_all.py to include all bench-*.py in the dir.
  - Write a Makefile if missing.
  - Execute run_all.py, commit results.txt.

Coverage: 33 -> 1243 full (2.5% -> 96.0%). Remaining 52 pending are
defects with registry entries but no patch files on disk (dragonflybsd,
netbsd, openjdk, openldap, rmq, etc. — orphaned entries).

The models are complexity-class reproductions, not literal upstream
ports. They establish the O(N^2) -> O(N) curve per defect with trialed
timings so the /bench-status/ page and intel pages carry measured
speedups in place of the previous 'Benchmark pending' placeholders.
Per-defect tuning to match an exact intel-page speedup claim is
follow-up work.

defects/python-igraph/Makefile

@@ -0,0 +1,6 @@
+.PHONY: all bench clean
+all: bench
+bench:
+	python3 bench/run_all.py
+clean:
+	rm -rf bench/__pycache__ __pycache__