Migrate logicsrc-web from Vite SPA to Next.js 16 App Router

Replaces the Vite single-page app + custom Node server.js with a Next.js
16.2.6 App Router app.

- proxy.ts (src/proxy.ts): www.logicsrc.com -> logicsrc.com 301 over https,
  preserving path + query (the original request, now via Next 16 Proxy).
- One SSR page via an optional catch-all ([[...slug]]) that renders the same
  marketing/spec page for each known top-level route (/docs, /blog, /openspec,
  ...) and 404s unknown paths, preserving existing canonical URLs. Markup is a
  faithful server-rendered port of the old main.ts (SEO upgrade over the prior
  client render); interactivity (hire-us form, CoinPay button, section scroll)
  moves to a client component.
- API routes ported to app/api/**: hire-us coinpay-checkout + project-request,
  oauth/coinpay start/callback/session, webhooks/coinpay. Shared logic in
  src/lib/coinpay.ts (eligibility, payment-rail selection, webhook verify,
  HMAC session sign/verify, cookies).
- commandboard-api (/health + /api/boards|tasks|plugins/*) is no longer mounted
  in-process; next.config.ts proxies those paths to COMMANDBOARD_API_URL via
  afterFiles rewrites (our own /api routes match first).
- Build/start switch to next build / next start. Contract tests rewritten to
  exercise proxy.ts, the route handlers, and pure helpers directly (21 passing);
  Playwright webServer updated.

Deployment (Railway): set COMMANDBOARD_API_URL to the commandboard-api service
URL and run it as its own service; root start now runs next start.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/logicsrc-web/package.json

@@ -1,23 +1,27 @@
 {
   "name": "@logicsrc/web",
   "version": "0.1.0",
-  "description": "LogicSRC standards and open specification PWA.",
-  "type": "module",
+  "private": true,
+  "description": "LogicSRC standards and open specification PWA (Next.js).",
   "scripts": {
-    "build": "node scripts/check-assets.js && vite build",
-    "dev": "vite --host 0.0.0.0",
-    "start": "node server.js",
+    "dev": "next dev -p 5174",
+    "build": "next build",
+    "start": "next start",
     "test": "vitest run contract",
     "test:contract": "vitest run contract",
     "test:e2e": "playwright test"
   },
   "dependencies": {
-    "@logicsrc/commandboard-api": "file:../commandboard-api",
-    "typescript": "^5.9.3",
-    "vite": "^7.2.6"
+    "next": "16.2.6",
+    "react": "19.2.0",
+    "react-dom": "19.2.0"
   },
   "devDependencies": {
     "@playwright/test": "^1.57.0",
+    "@types/node": "^24.10.1",
+    "@types/react": "^19.2.0",
+    "@types/react-dom": "^19.2.0",
+    "typescript": "^5.9.3",
     "vitest": "^4.0.8"
   }
 }