chore(#2453): resolve the uniform-router-param conflict and clear the warning floor (#2489)

npx eslint . reported 0 errors, 53 warnings. The floor eroded the signal: a
genuinely new warning had to be spotted against noise, so 'lint is clean' was not
usable as a check. This takes it to zero.

Fifty of the 53 were one category in gsd-core/bin/gsd-tools.cjs — all unused
ARGUMENTS (error x30, cwd x10, raw x7, args x3), never unused variables. They are
the Command Routing Hub's uniform handler signature, function routeX({ args, cwd,
raw, error }), declared identically whether or not a handler uses all four
members. argsIgnorePattern: '^_' is structurally in conflict with that convention:
satisfying it would mean _-prefixing ~50 parameters and making the signature
non-uniform across the table. Option 1 of #2453: disable args checking for that
file only, keeping varsIgnorePattern intact so genuinely dead variables (the #2379
class) still surface — verified by injecting an unused variable, which still warns.

This is the config decision #732 explicitly deferred ('Severities stay warn (no
config change in this pass)').

The remaining three predate the issue's count of 51 and are real defects, not
suppressions:

- tests/workflow-compat.test.cjs — the step-9 lookahead used (?=\*\*10\.|\z).
  \z is a Perl/Ruby end-of-input anchor with NO meaning in JavaScript; it matched
  a literal 'z', so the lazy span silently stopped at the first z whenever **10.
  was absent, truncating the captured step and letting the assertion pass against
  a partial block. Corrected to $.
- tests/debugger-prevention.test.cjs — an unused RegExp built one line above the
  one actually used. Removed.
- tests/installer-migrations.test.cjs — try/finally inside a test body, which
  CONTRIBUTING prohibits ('verbose, masks test failures, not an approved
  pattern'); the unused t was the symptom. Converted to t.after().

Closes #2453

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/workflow-compat.test.cjs

@@ -161,7 +161,11 @@ describe('feat-41: ship.md TDD Audit gate_status extraction', () => {
   test('#2431: step 9 (aggregate trailer) is also gated on real values existing', () => {
     // The aggregate gate_status trailer is the companion to the TDD Audit
     // section; both must be skipped together when no real gate_status exists.
-    const step9 = workflow.match(/\*\*9\.\s*Aggregate gate_status trailer[\s\S]*?(?=\*\*10\.|\z)/);
+    // `\z` is a Perl/Ruby end-of-input anchor with NO meaning in JavaScript — it
+    // matched a literal `z`, so the lazy span silently stopped at the first `z`
+    // whenever `**10.` was absent, truncating the captured step. `$` (no /m flag)
+    // is the JS end-of-input anchor.
+    const step9 = workflow.match(/\*\*9\.\s*Aggregate gate_status trailer[\s\S]*?(?=\*\*10\.|$)/);
     assert.ok(step9, 'step 9 must exist in the workflow');
     assert.match(step9[0], /step 8|at least one|real/i,
       'step 9 must reference step 8 or require at least one real gate_status value (#2431)');