chore: pin browserslist past GHSA-c83g-rgw3-j3cx in clients/tui (dev-only high advisory)

[cliffhall]

npm audit is clean in four of the five installs and reports 1 high in clients/tui:

browserslist  <=4.28.6
Severity: high
  GHSA-c83g-rgw3-j3cx — unbounded memory growth (no cache eviction) via distinct query results, eventual OOM
  GHSA-73wf-gq98-2v4g — uncaught crash / prototype write via untrusted browserslist-stats.json (normalizeStats)
node_modules/browserslist

Where it comes from

It is transitive, through the tui-local ESLint plugin:

@modelcontextprotocol/inspector-tui
└─┬ eslint-plugin-react-hooks@7.1.1
  └─┬ @babel/core@7.29.7
    └─┬ @babel/helper-compilation-targets@7.29.7
      └─┬ browserslist@4.28.2
        └─┬ update-browserslist-db@1.2.3
          └── browserslist@4.28.2 deduped

This is exactly the peer-shadow case AGENTS.md already documents under
Dependency placement: deleting a root-only
declaration does not delete the client copy, because npm auto-installs an unmet peer into
the install that needs it, and a client-only ESLint plugin drags a client-local tree in with it.

Nothing published is affected

• npm audit --omit=dev in clients/tui — 0 vulnerabilities.
• The tarball ships only each client's build/; pack:verify installs clean into a throwaway
  consumer and drives web/cli/tui end to end.

It is not new to v2.5.0

origin/main's tui lockfile pins the same browserslist@4.28.2, so v2.4.0 shipped with this
exact tree — the advisory was published since. The root (4.28.8) and clients/web
(4.28.7) copies float above the 4.28.7 fix line only because #2200 / #2196 refreshed their
lockfiles in this milestone while tui's was not touched.

So this is a reporting change, not a regression, and it does not block the v2.5.0 release
(#2214). But it does mean npm audit across the five installs is no longer clean, which is the
state #2062 established and which the v2.4.0 smoke ledger recorded.

Fix

Per AGENTS.md: pin a transitive with an overrides entry, not with npm audit fix —
which "resolves" an advisory with no upward escape by silently downgrading. clients/tui
already carries an overrides block (ink-select-input, esbuild), so this is one more entry:

"overrides": { "browserslist": "^4.28.7" }

Done when

• npm audit reports 0 vulnerabilities in all five installs, dev included
• npm audit --omit=dev still clean in all five
• npm run local:gate passes (the tui lint stage is what pulls the plugin in)

Found while smoke-testing the v2.5.0 payload — see the note on
#2215 (comment)

[cliffhall]

Triage: Priority Medium (total 6)

• Severity 2 — minor friction with an easy workaround. The advisory is real but the exposure is not: browserslist reaches only the tui dev install, npm audit --omit=dev is clean there, and the tarball ships only each client's build/. Neither GHSA is reachable in our use (we feed it no untrusted browserslist-stats.json, and the OOM is bounded by a lint run). What is actually broken is the invariant Dev-only esbuild advisory (GHSA-g7r4-m6w7-qqqr) keeps npm audit non-clean in web/cli/tui #2062 established — npm audit clean across all five installs, dev included.
• Urgency 3 — wanted this milestone. Nothing blocks on it and it does not affect the v2.5.0 release, but a permanently-dirty npm audit is a channel people learn to skim, which is the same argument Fail lint on warnings (--max-warnings 0): a warn-level rule let a stale-closure bug reach review #2085 and the build-output rule make.
• Bonuses: +1 security-related. Claimed on substance, not on the label: the type label is chore (correct — no user-facing behavior change), but the issue is a published CVE pair. Flagging it so a re-scorer can disagree with that call rather than have to reverse-engineer it.
• Not claimed: no bug label, no engagement yet, unassigned, not a sub-issue, and no milestone bonus — every issue filed through /issue-create carries a milestone by rule, so counting it here would make it a constant that discriminates nothing.

Band note: this scores Medium because it is dev-only and unshipped. Had the same advisory reached the published tarball it would be Severity 5 and land High or Urgent.

Board: #28, Status Todo, milestone v2.6.0.