refactor(test): migrate the 36 tier-gated eval files to describeE2ETier

Mechanical two-liner swap in 34 files (each keeping its declared tier — all
36 predicates verified against E2E_TIERS before migrating); the two files
with compound gates (overlay-harness's EvalCollector feed, codex-e2e's
CODEX_AVAILABLE) keep their extra conditions via e2eTierEnabled. Tier
rationale comments preserved. codex-e2e/gemini-e2e/benchmark-providers keep
their distinct stderr-message gate shapes by design.

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

test/skill-e2e-ship-idempotency.test.ts

@@ -30,7 +30,8 @@
  * Cost: ~$2-4/run. Periodic tier — long, runs weekly.
  */
 
-import { describe, test, expect } from 'bun:test';
+import { test, expect } from 'bun:test';
+import { describeE2ETier } from './helpers/e2e-gate';
 import { spawnSync } from 'child_process';
 import * as fs from 'fs';
 import * as path from 'path';
@@ -41,8 +42,7 @@ import {
   isNumberedOptionListVisible,
 } from './helpers/claude-pty-runner';
 
-const shouldRun = !!process.env.EVALS && process.env.EVALS_TIER === 'periodic';
-const describeE2E = shouldRun ? describe : describe.skip;
+const describeE2E = describeE2ETier('periodic');
 
 interface ShipFixture {
   workTree: string;