docs: CHANGELOG accuracy fixes from the doc-release review

Three factual corrections the Step 18 doc subagent caught in the fresh
v1.70.1.0 entry: 5 tripwire tests (not 6), cost floor $0.63 per the cited
eval store (not $0.59), and the visibility claim scoped to decision points
(the re-run checklist mention survived the carve). Plus the E2E header's
stale pending-burn-in note replaced with the observed numbers.

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

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

@@ -45,7 +45,8 @@
  * test would make the assert tautological (and the prompt echoes into the
  * transcript, which is why asserts only ever read result.toolCalls).
  *
- * Cost: ~$0.30-1/run. Gate tier (pending burn-in; see plan).
+ * Cost: observed $0.63-1.04/run, 234-319s (9/9 burn-in + review runs passed;
+ * gate tier confirmed).
  */
 import { expect, beforeAll, afterAll } from 'bun:test';
 import * as fs from 'fs';