fix(1259-01): close adversarial review findings — genuine enforcement, honest fail-first scope

Adversarial pre-submission review found the injected-runCheck tests masked a
non-functional real runner. Fixes:

- BL-01 (false green on vacuous test): the node-test runner now parses the TAP
  summary and requires a NON-VACUOUS pass (>=1 test, >=1 pass, 0 fail) AND a
  reported test named distinctly from the file — node --test counts an empty file
  as one passing test, so counts alone could not catch it.
- SF-01 (lint anchor never greened): the lint-rule runner now runs the project
  eslint as --format json and filters by ruleId, so plugin rules (local/*) load
  via the flat config — bare --rule cannot load a plugin. local/no-source-grep
  now genuinely greens (covered by a real, non-injected test).
- BL-02 (tautological fail-first): the runner no longer echoes the caller's
  failFirst as if confirmed. failFirst is documented as caller-ATTESTED; the
  producer requires attestation + a genuine non-vacuous pass. Machine-proven
  fail-first (needs a violation fixture) is flagged as a tracked follow-up in
  ADR-550, the changeset, FEATURES, the reference doc, and verify-phase.
- SF-02: added real-runner end-to-end tests (no injected runCheck) + pure,
  exported parse/filter helpers (parseNodeTestSummary, tapTestNames,
  eslintJsonHasRule, eslintFileResultCount) so the shipping branches are
  mutation-pinned.
- NIT-01/02: LOCATE guard rejects empty-string rule and unknown kinds.
- Hardening: spawn checks with NODE_TEST_CONTEXT/NODE_OPTIONS scrubbed so an
  ambient test-runner context cannot corrupt a verify-time result.
- Docs reconciled to the shipped behavior (no 'confirms fail-first' overclaim).

docs/FEATURES.md

@@ -3180,6 +3180,6 @@ The load-bearing wire is the `plan-phase` lift into `must_haves.prohibitions`, s
 - REQ-PROHIB-04: `--auto` MUST never auto-dismiss.
 - REQ-PROHIB-05: `plan-phase` MUST lift resolved prohibitions into `must_haves.prohibitions` (never `truths`).
 - REQ-PROHIB-06: A well-formed but unwired `test`-tier prohibition MUST fail closed at verify time — never a silent pass.
-- REQ-PROHIB-07: A `test`-tier prohibition with a PASSING wired mechanical check (a `node --test` negative test OR a lint/AST rule) MUST dispose green and be satisfiable; a missing or failing check MUST hard-gate (flagged, non-green) in both interactive and autonomous modes (#1259, ADR-550 D5d — the enforcement half).
+- REQ-PROHIB-07: A `test`-tier prohibition with a caller-attested, genuinely-passing (non-vacuous) wired mechanical check (a `node --test` negative test OR a lint/AST rule) MUST dispose green and be satisfiable; a missing, non-attested, or non-passing check MUST hard-gate (flagged, non-green) in both interactive and autonomous modes (#1259, ADR-550 D5d — the enforcement half; machine-proven fail-first is a tracked follow-up).
 
 **Reference:** [Prohibition Probe](../gsd-core/references/prohibition-probe.md)