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).

gsd-core/workflows/verify-phase.md

@@ -76,9 +76,9 @@ Aggregate all must_haves across plans for phase-level verification.
   gsd_run check prohibition-enforcement <request.json>
   ```
 
-  where `<request.json>` carries `{ prohibition, check, mode }` — `check` being the wired mechanical-check descriptor `{ kind: 'node-test' | 'lint-rule', target, rule?, failFirst: true }`. For `node-test`, `target` is the negative-test file path; for `lint-rule`, `target` is the PATH to lint and `rule` is the eslint rule id (e.g. `local/no-source-grep`) — both required (a lint-rule without `rule` is not a valid wired check). The producer LOCATES the wired check, CONFIRMS it is fail-first (`regression-must-fail-first`), RUNS it, builds `enforcementEvidence`, and emits the `dispositionForProhibition()` verdict (#1259, ADR-550 D5d). Route the result by its typed fields:
-  - **`status: 'green'`, `flagged: false`** (a passing wired negative test / lint rule, `located: true`, non-empty `evidence`) → the item is satisfiable → it can reach **passed**.
-  - **missing, failing, or non-fail-first check** (`located: false` OR `status: 'unverified'`, `flagged: true`) → **hard-gate**: disposes flagged-unverified, NEVER green, routing to `gaps_found` in BOTH interactive and autonomous modes (a failing mechanical check blocks even AFK; ADR-550 D4 / D3). The deterministic fail-closed default backing every miss/fail is `dispositionForProhibition()` in probe-core (`status: 'unverified'`, `flagged: true` on empty `enforcementEvidence`).
+  where `<request.json>` carries `{ prohibition, check, mode }` — `check` being the wired mechanical-check descriptor `{ kind: 'node-test' | 'lint-rule', target, rule?, failFirst: true }`. For `node-test`, `target` is the negative-test file path; for `lint-rule`, `target` is the PATH to lint and `rule` is the eslint rule id (e.g. `local/no-source-grep`) — both required (a lint-rule without `rule` is not a valid wired check). The producer LOCATES the wired check, requires the caller-attested `failFirst` marker, RUNS it for a genuine non-vacuous pass, builds `enforcementEvidence`, and emits the `dispositionForProhibition()` verdict (#1259, ADR-550 D5d). (`failFirst` is caller-attested, not yet machine-proven against a violation fixture — a tracked follow-up.) Route the result by its typed fields:
+  - **`status: 'green'`, `flagged: false`** (a genuinely-passing wired negative test / lint rule, `located: true`, non-empty `evidence`) → the item is satisfiable → it can reach **passed**.
+  - **missing, non-attested, or genuinely-non-passing check** (`located: false` OR `status: 'unverified'`, `flagged: true`) → **hard-gate**: disposes flagged-unverified, NEVER green, routing to `gaps_found` in BOTH interactive and autonomous modes (a failing mechanical check blocks even AFK; ADR-550 D4 / D3). The deterministic fail-closed default backing every miss/fail is `dispositionForProhibition()` in probe-core (`status: 'unverified'`, `flagged: true` on empty `enforcementEvidence`).
 
 **Option B: Use Success Criteria from ROADMAP.md**