fix(test): delete the superseded SDK ship-idempotency suite and three orphaned fixtures

test/skill-e2e-ship-idempotency.test.ts's own header documented that the
monolith's SDK-harness version tests a synthetic prompt while it exercises
the real /ship skill — the author knew the old suite was superseded and left
both running, two paid LLM runs for one behavior. The weaker copy is gone;
its 'ship-idempotency' diff-selection key goes with it (the dedicated file is
periodic-tier, which always runs under EVALS_ALL — the key had no remaining
consumer).

Fixture rot: test/fixtures/golden-ship-claude.md was a 128KB zero-reader
orphan that had drifted 46KB from its live successor
(test/fixtures/golden/claude-ship-SKILL.md) while looking authoritative;
parity-baseline-v1.46.0.0.json and v1.53.0.0.json had zero readers (three
tests pin three OTHER baseline versions — consolidation is queued, deletion
of the unreferenced two is free).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/helpers/touchfiles.ts

@@ -295,7 +295,6 @@ export const E2E_TOUCHFILES: Record<string, string[]> = {
   // Plan completion audit + verification
   'ship-plan-completion': ['ship/**', 'scripts/gen-skill-docs.ts'],
   'ship-plan-verification': ['ship/**', 'qa-only/**', 'scripts/gen-skill-docs.ts'],
-  'ship-idempotency':       ['ship/**', 'scripts/resolvers/utility.ts'],
   'review-plan-completion': ['review/**', 'scripts/gen-skill-docs.ts'],
 
   // Design
@@ -652,7 +651,6 @@ export const E2E_TIERS: Record<string, 'gate' | 'periodic'> = {
   'ship-triage': 'gate',
   'ship-plan-completion': 'gate',
   'ship-plan-verification': 'gate',
-  'ship-idempotency': 'periodic',
 
   // Retro — gate for cheap branch detection, periodic for full Opus retro
   'retro': 'periodic',