Fix backend TypeScript build errors

- Inline tsconfig.base.json settings into backend/tsconfig.json so the
  Docker build (which only copies backend/) can resolve them
- Replace default imports of Node built-ins (crypto, net) with named imports
- Replace default bcrypt import with named imports (compare, hash)
- Switch @fastify/websocket from v8 to v7 (SocketStream API) to match
  Fastify v4 peer dependency; update WebSocket handler signatures accordingly
- Remove obsolete `version` key from docker-compose.yml

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

backend/src/routes/auth.ts

@@ -1,5 +1,5 @@
 import { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify';
-import bcrypt from 'bcryptjs';
+import { compare as bcryptCompare } from 'bcryptjs';
 
 interface LoginBody {
   username: string;
@@ -30,7 +30,7 @@ export async function authRoutes(fastify: FastifyInstance) {
         return reply.status(401).send({ error: 'Invalid credentials' });
       }
 
-      const valid = await bcrypt.compare(password, user.passwordHash);
+      const valid = await bcryptCompare(password, user.passwordHash);
       if (!valid) {
         return reply.status(401).send({ error: 'Invalid credentials' });
       }