Upgrade to Next.js 16.3

[vdvman1]

Question

Nothing to decide about whether — but the caching architecture decision cannot be made concretely against an API the repo is not on, so this unblocks it.

Currently on next@16.0.3 / eslint-config-next@16.0.3, React 19.2.0.

Scope:

• Bump next and eslint-config-next to 16.3.x.
• Work through any breaking changes; get npm run check (eslint + tsc) and npm run build green.
• Do not enable cache components or touch src/lib/fetch.ts — that belongs to the rendering and caching architecture ticket.

Known landmines:

• Turbopack. package.json pins next build --webpack and next dev --webpack; Next 16 defaults to Turbopack. next.config.js carries a hand-rolled SVGR webpack rule that Turbopack will not run. Turbopack is explicitly not a blocker — if the SVGR port is easy, take it; otherwise stay on --webpack and leave a note. Do not let this hold up the upgrade.
• src/app/java/changelog/page.tsx:8 has a force-dynamic hack. Leave it in place. Note whether 16.3 changes its behaviour — the last comment on Java Changlogs caching too strongly #4 speculated that a Next upgrade might fix the underlying ISR mis-detection.

Record in the resolution: the version landed on, what broke, whether Turbopack was taken, and any observed change in the force-dynamic behaviour.

[vdvman1]

Note from #30 (cache components research).

This ticket deliberately does not enable cache components — but be aware the follow-on will, and cacheComponents makes export const dynamic a build error. The repo has two such exports: src/app/java/changelog/page.tsx:9 (the hack, tracked by #4) and src/app/about/advanced/page.tsx:12 (legitimate — reads runtime env vars).

Leave both in place here. Just record in the resolution whether 16.3 changes the force-dynamic behaviour on the changelog page, per the original ticket text.