[Phase 2] Roll out Next 16 + findable-ui major upgrade across all consumers

[frano-m]

Parent: #884 (Next.js 16 Upgrade Plan)

Context

Phase 1 of the Next 16 upgrade (#884) lands in findable-ui as a major release: peer dep pinned to next ^16, next-mdx-remote ^6, react-hooks v7 + ESLint v16, plus several breaking API changes (e.g. removal of useResetableState, removal of superseded from FilterTag / CategoryTag via #951).

This ticket tracks rolling that release out to every downstream consumer.

Consumers

Suggested upgrade order (smallest → largest; hca-atlas-tracker last because it pulls in the next-auth v4 → Auth.js v5 question):

1. ucsc-brain-explorer
2. hprc-data-explorer
3. ncpi-dataset-catalog
4. data-portal
5. data-biosphere
6. brc-analytics
7. anvil-portal
8. hca-atlas-tracker

Each gets a single PR in its own repo bundling the steps below.

Per-consumer checklist

Reference: .claude/plans/884-next-16/next-16-upgrade-plan.md §10 Phase 2 and the README "Consumer setup for Next.js 16" + "Migrating from Next.js 15 to 16" sections.

• Bump dependencies:
  • next → ^16
  • eslint-config-next → ^16
  • @next/eslint-plugin-next → ^16
  • next-mdx-remote → ^6 (non-optional peer dep of findable-ui)
  • @databiosphere/findable-ui → the new major release
• Install MUI's Emotion helpers (new): npm install @mui/material-nextjs @emotion/server
• Wire pages/_app.tsx: wrap in AppCacheProvider from @mui/material-nextjs/v16-pagesRouter
• Wire pages/_document.tsx: add DocumentHeadTags + documentGetInitialProps
• Pin builds to webpack: change next dev / next build scripts to next dev --webpack / next build --webpack (tracking vercel/next.js#82607)
• If the consumer calls next-mdx-remote/serialize directly (not via findable-ui's buildStaticProps), pass blockJS: false
• Migrate .eslintrc.json → eslint.config.mjs (flat config). findable-ui's own eslint.config.mjs is the reference implementation
• Bump Node baseline (.nvmrc, CI workflows, Dockerfile FROM node:...) to whatever findable-ui's package.json engines.node is at the time of the release
• Run npx @next/codemod@canary upgrade latest as a safety net for any pattern not explicitly handled above
• Audit for findable-ui API removals (e.g. useResetableState, superseded on FilterTag / CategoryTag) and update call sites
• Verify next build --webpack succeeds
• Run unit tests + Playwright e2e
• Deploy to staging and smoke test

Special concerns

• hca-atlas-tracker still on next-auth ^4. Either confirm v4 works under Next 16 or migrate to Auth.js v5 as part of this upgrade. Worth verifying upstream before scheduling the PR.

Acceptance

• All 8 consumers running next ^16 and the new findable-ui major, with their CI green and a staging smoke-test pass logged.
• Any findable-ui-side blockers surfaced during the rollout are filed back here as follow-ups.

Notes

• The release itself: track via release-please on findable-ui main. CHANGELOG entries from the Phase 1 PRs (peer dep bump, react-hooks v7 cluster, etc.) feed the release notes automatically — see [P1.10] Next.js 16 prep: CHANGELOG + peer-dep guidance for consumers #935 for the consumer-facing migration guide.

[frano-m]

Heads-up surfaced during ucsc-brain-explorer (#107): consumers that use eslint-plugin-typescript-sort-keys need to swap it out.

The plugin's latest release is 3.3.0 and its peer dep is pinned to eslint ^7 || ^8. The maintainer hasn't shipped ESLint v9 support. npm install only warns — it'll complete — but npm audit fix is stricter and refuses to rewrite the tree while the peer conflict is unresolved, blocking any vulnerability cleanup downstream.

Recommended fix (matches findable-ui's own eslint.config.mjs): replace it with eslint-plugin-perfectionist ^4 and switch the rules:

- plugins: [..., "typescript-sort-keys"]
+ plugins: [..., "perfectionist"]

- "typescript-sort-keys/interface": ["error", "asc", { caseSensitive: false }],
- "typescript-sort-keys/string-enum": ["error", "asc", { caseSensitive: false }],
+ "perfectionist/sort-enums": "error",
+ "perfectionist/sort-interfaces": "error",

Suggested addition to the per-consumer checklist (insert near the ESLint flat-config item):

• If the consumer's lint setup uses eslint-plugin-typescript-sort-keys, replace it with eslint-plugin-perfectionist ^4 (matching findable-ui's eslint.config.mjs). Required to unblock npm audit fix under ESLint v9.

Worth grepping the remaining 7 consumers for typescript-sort-keys before scheduling each PR.