BLD-002 R12-D: Python off dogfood and the perf, bench and parity receipts #4695

Ticket R12-D of the BLD-002 R12 list (cop-inbox handoff/bld-002-r12-propose-tickets.md), verbatim. Sub-tickets are checklist lines (ISSUE-TREE-001: subs do not count).

R12-D: dogfood and the receipts it reads (S09)

aprender: Python off dogfood and the perf, bench and parity receipts. 12 files, 7256 lines.

• D1 dogfood (5 files, 1449 lines): dogfood_coverage_gate.py 949, scripts/dogfood_baseline.py 225,
  scripts/invariance.py 153, dogfood_gates.py 84, scripts/dogfood_the44.py 38. Relates to R6, the dogfood split;
  dogfood: coverage note prints the floor from the shell (default 88) while make enforces 89 #4671 folds into R6 per C294.6.
• D2 perf receipts (4 files, 3649 lines): perf_receipt.py 1662, scripts/perf041_batched_parity_probe.py 964,
  receipt_sig.py 800, scripts/perf041_client.py 223.
• D3 bench and parity receipts (3 files, 2158 lines): parity_block.py 1043, bench_receipt.py 872, bench_threshold.py 243.

Common to every ticket (so each body stays short):

• The replacement is bash plus awk, or in-tree Rust (an apr or pv subcommand, or a crate binary). No new Python (spec §6).
• Falsifier: the R12 guard on the PR, --check --base <base> --head <head>, is GREEN, and the area's files leave the
  inventory (python_files falls by the area's count; interp_lines does not rise). Plus a parity row: the replacement
  gives the old tool's verdict on recorded inputs, including at least one planted RED input.
• Shadow first: the replacement runs beside the old tool for 3 green nights before the old tool is removed
  (C280.12; spec P6).
• Anything on the publish path: clean-room first (spec §6).

Paths are under scripts/lib/ unless another directory is given.

Inventory: bash scripts/check_release_path_python.sh --inventory --rev 316dee2cd4 (branch build-kaizen/bld002-r12). Ticket R12-E (the guard) is #4684.

Not an exit criterion for 0.70.2 (R12 row), so P1 under the 0.70.2 epic. Owner: aprender-a7. Minted by the cop's clerk.