fix(ai): restore shared CLI helper contracts

[lusoris]

Summary

Restores the accepted ADR-0680/0681 shared bootstrap, parser, and replay-argv
contract across twelve current tiny-AI evaluation, quantization, and export
scripts without replacing their later CLI or provenance behavior. Adds an AST
red-cap plus direct-file/module probes so a future silent revert fails closed.

This is intentionally stacked on #1552: that parent repairs the fail-closed
pre-push mypy baseline/configuration gate used to validate this Python-heavy
restoration.

Type

• feat — new feature
• fix — bug fix
• perf — performance improvement
• refactor — no behavior change
• docs — documentation only
• test — test-only
• build / ci — tooling / infra
• port — cherry-pick from upstream Netflix/vmaf
• sycl / cuda / simd — backend-specific

Checklist

• Commits follow Conventional Commits and are signed.
• make format && make lint — aggregate targets not run; Black 26.5.1,
  Ruff 0.16.8, changed-file pre-commit, make verify-all, and the complete
  normal pre-push gate are green.
• Unit tests pass: meson test -C build — no native/Meson code changed;
  the affected Python suites are green below.
• Cross-backend diff — not applicable: no SIMD/GPU implementation changed.
• Feature-extractor twin update — not applicable: no extractor changed.
• New native-file license header — not applicable: no native file added.
• This is not a breaking change.
• ADR index update — not applicable: bug-fix implementation restores two
  already-accepted ADRs and makes no new architectural decision.

Bug-status hygiene

• docs/state.md records
  T-BUG048-AI-CLI-HELPERS-REVERTED-2026-09-24 as closed while explicitly
  keeping BUG-048 open for its remaining restoration sections.

Netflix golden-data gate

• No Netflix assertAlmostEqual(...) golden score was modified.
• Golden-value exception — not applicable.

Cross-backend numerical results

Not applicable; this change touches Python CLI/bootstrap behavior only.

Performance

Not applicable; no benchmark, tuning, training, or inference hot path changed.

Deep-dive deliverables

• Research digest — docs/research/2088-bug048-ai-cli-helper-restoration.md.
• Decision matrix — digest records the only-way restoration and rejects
  whole-commit replay and globally widening the bootstrap default.
• AGENTS.md invariant note — ai/AGENTS.md pins the twelve-script
  bootstrap/parser/replay contract and include_repo_root=True boundary.
• Reproducer / smoke-test command — pasted below under Reproducer.
• CHANGELOG fragment —
  changelog.d/fixed/bug048-ai-cli-helper-restoration.md plus its generated
  Unreleased rendering.
• Rebase note — docs/rebase-notes.md records the preserved seam and
  semantic regression.

Reproducer

python -m pytest \
  ai/tests/test_ai_cli_helper_restoration.py \
  ai/tests/test_eval_report_run_provenance.py \
  ai/tests/test_legacy_eval_report_run_provenance.py \
  ai/tests/test_qat_smoke.py \
  ai/tests/test_ptq_scripts.py \
  ai/tests/test_measure_quant_drop_per_ep.py \
  ai/tests/test_dnn_exporter_run_provenance.py -q

Validation

• focused helper/provenance/QAT/PTQ/exporter suite: 34 passed after the final
  writable AGY corrections;
• semantic restoration red-cap: 12 passed;
• direct-file and python -m --help: 24/24 passed;
• complete ai/ package before publication: 1,315 passed, 1 skipped;
• fail-closed pre-push mypy: 0 introduced findings, 601 inherited findings;
• Black and Ruff: clean;
• make verify-all: green, HISS 264 within the 276 baseline;
• writable AGY final audit: PASS after correcting seven introduced mypy
  findings; and
• normal pre-push: green in 240.32 seconds, including strict MkDocs, security,
  HISS, dedupe, formatting, and PR-body governance.

Known follow-ups

• This PR is stacked on fix: restore AI CLI helpers and align mypy pre-push gate #1552 and must merge after it.
• BUG-048 remains open for its other independently reviewed restoration chunks.
• Benchmarking, performance tuning, and retraining remain deliberately out of
  scope until correctness and security cleanup completes.

Breaking changes / migration

None.