docs(changelog): note the 5 gate-eval hardenings in For contributors

Adds a line to the v1.32.0.0 entry's For contributors section summarising
the five gate-tier eval hardenings that landed alongside the wave —
office-hours-builder-wildness retiers to periodic, plan-design-with-ui
AUQ-detection tail expands 5KB, ask-user-question-format-compliance
budgets stretch, gemini smoke shape-checks instead of grepping 'ok',
skillify scrape-prototype-path accepts JSON shape variants.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -49,6 +49,7 @@ If you run `pair-agent` and someone hits your tunnel with a multibyte token gues
 
 - The AskUserQuestion preamble byte budget ratchets from 36,500 → 39,000 to absorb the new CJK rule (rule 12 + self-check item). Generated SKILL.md files for all 35 tier-≥2 skills regenerate as a single mechanical commit.
 - Two PRs from the original 9-PR plan moved to follow-up reviews after Codex outside-voice caught load-bearing problems: #1153 (SVG sanitizer) needs the sanitizer integration rebuilt against the current `setTabContent` boundary in `browse/src/write-commands.ts:319` (the original PR removed `.svg` from the allowlist; the right fix is to keep it allowed and sanitize via DOMPurify before `setTabContent`). #1141 (CLAUDE_PLUGIN_ROOT) needs runtime verification in both plugin-installed and dev-symlink modes plus scope expansion to the non-frontmatter shell snippet at `investigate/SKILL.md.tmpl:107`.
+- Five gate-tier evals hardened against non-determinism / TTY rendering quirks after the wave's first `test:gate` run surfaced them as flakes (verified pre-existing on `main`, then fixed): `office-hours-builder-wildness` retiers `gate` → `periodic` because LLM-judge creativity scoring belongs in periodic per the tier-classification rules. `plan-design-with-ui` AUQ-detection tail expands 2.5KB → 5KB so the full Step 0 box-rendered AUQ fits inside the regex window. `ask-user-question-format-compliance` budget stretches 300s → 540s (poll), 360s → 600s (PTY session), 420s → 660s (bun wrapper) to accommodate `/plan-ceo-review`'s multi-bash-block preamble on substantive branches. `benchmark-providers` gemini smoke drops the brittle `toContain('ok')` assertion in favor of a shape check on the adapter result. `skillify` scrape-prototype-path accepts JSON shape variants (`results`, `data`, `hits`, bare arrays of `{title, score}` objects) instead of grepping for the literal `"items":[` key.
 - Housekeeping: the three source PRs absorbed into v1.31.1.0 (#1242, #1394, #1393) get closed with credit comments pointing at the merge SHA.
 
 ## [1.31.1.0] - 2026-05-10