test(W7c): drop coverage-audit checklist tool-call prose pins

W7c conversion (t05 F11; unblocks s06 L9). Pin lines 17 -> 14.

Removed assertion group (invariant -> remaining protection):
- review/specialists/testing.md prose pins 'If the caller explicitly asks
  for an ASCII coverage diagram', 'dedicated tool call' and /Read diffs,
  package files, configs, or other context in separate tool calls\./ (tool-use
  choreography): the agent reads the named source and test files before
  drawing the diagram -> kept free: the same test still extracts the
  checklist's example diagram and requires coverageAuditVerdict to accept it
  (sourceRead/testsRead/diagram/passed), plus the kept [OK]/[GAP] row and
  legend pins; gate-tier E2Es review-coverage-audit, plan-eng-coverage-audit
  and ship-coverage-audit (E2E_TIERS: gate) grade the reads from transcript
  evidence with the same oracle.

Mutation pass (scratch worktree, review/specialists/testing.md): 6/6 as
expected; reordered diagram rows, deleted legend, deleted [OK] marker and a
removed text fence go red; two rewordings of the dropped tool-call sentences
stay green. Log: .context/mutation-coverage-audit.md.

test/coverage-audit.test.ts

@@ -167,9 +167,6 @@ test('diagram accepts an explicit single GAP legend mixed with quality keys', ()
 
 test('review testing checklist documents a coverage diagram shape accepted by the native oracle', () => {
   const checklist = fs.readFileSync(path.join(ROOT, 'review/specialists/testing.md'), 'utf8');
-  expect(checklist).toContain('If the caller explicitly asks for an ASCII coverage diagram');
-  expect(checklist).toContain('dedicated tool call');
-  expect(checklist).toMatch(/Read\s+diffs, package files, configs, or other context in separate tool calls\./);
   expect(checklist).toContain('valid USD happy path returns success [OK]');
   expect(checklist).toContain('refund success and guard branches not imported or untested [GAP]');
   expect(checklist).toContain('Legend: [OK] tested [GAP] no test');