feat(screens): Next.js as a Screens app — pages, route handlers, links and redirects

- frameworks/nextjs.ts (split out of react.ts): App Router app/**/page.tsx and Pages Router pages → routes named by path ((group) stripped, [slug] → :slug, [...all] → :all*), bound to the default export; app/**/route.ts exports → METHOD /api/… endpoints referencing their functions; pages/api → ANY; resolve() claims router.push/replace/prefetch, redirect/permanentRedirect and NextResponse.redirect(new URL(…)) into navigates edges via the Expo href readers, against a Next-only route table gated on the app's root
- next-router-synthesizer.ts: <Link href> and internal <a href> → dashed navigates edges from the component (next-link, registeredAt)
- expo-router.ts: href readers exported; matcher accepts :param / :all* segments
- steps.ts: a Next page's own work fires from page load; a Next page makes the project a web app; {status: 201} read off the call site (branch-guards CallSiteText.status) for response rows
- frameworks/package-deps.ts: nested package.json files probed on disk (getAllFiles lists only sources); Express/React/Expo/Nest detectors use it; routing manifest names constant handlers
- tests: nextjs.test.ts (file→route rules, extract, verbs, end to end with Screens and Steps); frameworks.test.ts Next cases moved to the Next resolver
- docs: CHANGELOG, spec §3.12 frameworks paragraph, CLAUDE.md, synthesis doc, plan P4 built, playbook rows for Next / MERN / Nest channels

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01REFyW9hmNrxhwN5wxRoAkC

docs/design/codegraph-ui-design-spec.md

@@ -440,6 +440,18 @@ for a pair with several. Placement: at the FAR end of the line; first lane centr
 lane; never over a box; overflow counted in the panel. Panel row hover: that pill prints the whole condition (wraps at
 360px), its line at 1.0, the rest at 0.38; a hovered line tints its row `--press`. Legend bottom-left, remembered per browser.
 
+**Frameworks.** The picture is a pure function of `route` nodes bound to the component that renders them and `navigates` edges
+from the function that pushes a path to the route it names, so any framework that produces those facts lands here. Expo Router
+(`resolution/frameworks/expo-router.ts`): `app/**` screen files, `router.push` / `navigate` / `replace` and a helper's return value.
+Next.js (`frameworks/nextjs.ts`, `next-router-synthesizer.ts`): App Router `app/**/page.tsx` and Pages Router pages (`(group)`
+stripped, `[slug]` → `:slug`, `[...all]` → `:all*`; `@slot` and `(.)intercepting` routes not modelled), bound to the default export;
+`router.push` / `replace` / `prefetch`, `redirect` / `permanentRedirect`, `NextResponse.redirect(new URL(…))` read like an Expo href
+(string, template with holes, `{ pathname }`, a conditional whose arms agree, a local `const href`) and matched against the Next
+pages only, from files under a Next app's root; `<Link href>` and an internal `<a href>` are markup, not calls, so a synthesizer
+reads them and draws a dashed `navigates` edge from the component (`synthesizedBy: 'next-link'`, the site as `registeredAt`).
+`app/api/**/route.ts` exports and `pages/api/*` are endpoints, not screens (`POST /api/users`, `ANY /api/users`), so the same
+index is a web app: pages on this tab, endpoints in Entry points, and a page's Steps picture firing from its load.
+
 ### 3.13 Steps (`#/steps?anchor=<id>` | `?symbol=<name>`, `&depth=`)
 What happens from an anchor — a screen, a handler, any symbol — drawn with the Screens view's machinery (§3.12's
 layout, tracks, pills, nearest-line pointer, panel) over a different node universe. `/api/steps` walks FORWARD from