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

CHANGELOG.md

@@ -14,6 +14,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### New Features
 
+- **A Next.js app lands on the Screens tab like a mobile app.** App Router pages (`app/(group)/blog/[slug]/page.tsx` → `/blog/:slug`) and Pages Router pages are screens bound to the component they export; `<Link href>`, an internal `<a href>`, `router.push` / `router.replace` (`next/navigation` and `next/router`), `redirect()` / `permanentRedirect()` in a server action or a page, and the middleware's `NextResponse.redirect(new URL('/login', req.url))` are the transitions between them — each attributed back to the page it starts on with the plumbing folded and the condition on the arrow, a link written in markup drawn dashed as an inferred hop. `app/api/**/route.ts` exports (`GET`, `POST`, …) are endpoints bound to their functions, `pages/api/*` handlers are `ANY /api/…`, and a page's Steps picture fires from its load (`FIRES FROM page load · /users`), draws the data it reads, the handlers it wires, the server actions it crosses to and the pages it leads to as boundaries. A response's status written as `{ status: 201 }` is read too. Re-index after upgrading.
+
 - **The Steps tab follows a web app across its tiers.** A page's `fetch('/api/users', { method: 'POST' })` (or an `axios` / `ky` / `got` / `$fetch` call, including one through a project instance made with `axios.create({ baseURL })`) now reaches the route that serves it in the same index — drawn as a crossing to the server (`⇢ POST /api/users`) with the handler named on the box and the registration site in the panel, a boundary by default and entered with *Continue through*, so the picture reads page → handler → the endpoint → its database write → its response. A job put on a BullMQ / Bull queue lands on the `@Process` method, `Worker` or `queue.process` handler that consumes it; a NestJS `EventEmitter2` event lands on its `@OnEvent` listeners (globs included); a socket message crosses from a client's `socket.emit` to the gateway's `@SubscribeMessage` and back from the server's `emit` to the component that registered `socket.on`; and a Next.js server action called from a client file is a crossing to the server by its `'use server'` directive. Each of these is a synthesized hop — dashed, with where it was wired up — and `codegraph_explore`'s Flow section names them too. Only a literal path or event name pairs: a variable url, a path no route serves, or one two routes serve alike produce nothing. Re-index to pick the new edges up.
 
 - **The Steps tab now draws an API as well as an app.** Anchor on an endpoint — `POST /users` in Express, NestJS, Fastify, FastAPI, Flask, Django, Spring (Java or Kotlin), ASP.NET, Vapor or Gin — and the viewer starts at the handler the route runs (or at the route itself when the handler is an inline arrow), says what fires it (`FIRES FROM POST /users · after authenticate, validate(…)` — the middleware arguments at the registration, or the guard decorators on the method and its class, or a FastAPI `dependencies=[…]`), and draws what the request sets in motion: the database calls with the model and whether they read or write (`prisma.user.create({ data })` · `database · user · write`), jobs put on a queue, emails, payments, cache reads, token checks, calls to other services, files and processes — and the **responses**, one box per handler whose label is the status codes it can send (`201 · 404`) and whose panel rows are the endpoint's contract as the code has it: `WHEN NOT user → 404 · NotFoundException('no such user')`, `always → 201 · res.status(201).json(user)`. A queue consumer or a scheduled job anchored by name says the decorator that fires it (`@Process('email')`). The legend, the panel and the chooser use the project's own words — endpoint, data call, another tier — and the bare Steps tab lists an API's endpoints by router file when there are no screens. Re-index is not needed: everything new is read from the source at request time.