feat(web-next): custom Node server hosting Next.js + Socket.IO on port 3000

Replaces `next dev` / `next start` with a custom Node http server that
co-hosts Next.js and Socket.IO on the same port, wiring in the
RealtimeHandlerRegistry and session-cookie-based IRealtimeAuthenticator.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pnpm-lock.yaml

@@ -157,6 +157,9 @@ importers:
       '@repo/core-events':
         specifier: workspace:*
         version: link:../../packages/core-events
+      '@repo/core-realtime':
+        specifier: workspace:*
+        version: link:../../packages/core-realtime
       '@repo/core-shared':
         specifier: workspace:*
         version: link:../../packages/core-shared
@@ -202,6 +205,9 @@ importers:
       reflect-metadata:
         specifier: ^0.2.2
         version: 0.2.2
+      socket.io:
+        specifier: ^4.7.0
+        version: 4.8.3
       superjson:
         specifier: ^2.2.1
         version: 2.2.6
@@ -239,6 +245,9 @@ importers:
       jsdom:
         specifier: ^25.0.0
         version: 25.0.1
+      tsx:
+        specifier: ^4.0.0
+        version: 4.21.0
       vitest:
         specifier: ^3.0.0
         version: 3.2.4(@types/debug@4.1.13)(@types/node@22.19.17)(happy-dom@20.8.9)(jiti@2.6.1)(jsdom@25.0.1)(lightningcss@1.32.0)(sass@1.99.0)(terser@5.46.2)(tsx@4.21.0)
@@ -14856,7 +14865,7 @@ snapshots:
   tsx@4.21.0:
     dependencies:
       esbuild: 0.27.7
-      get-tsconfig: 4.8.1
+      get-tsconfig: 4.13.7
     optionalDependencies:
       fsevents: 2.3.3