Fix prod docker build: native modules and frontend devDeps

Per-package onlyBuiltDependencies so pnpm 10 actually compiles native
modules (isolated-vm, argon2, sqlite3, sharp) — root workspace config
isn't visible when compose mounts a single package into /app.

Frontend container now installs with devDeps (so tsc/vite exist),
prunes after build, and gains a `start` script that serves the build
via vite preview on 0.0.0.0:3000.

Drop obsolete compose `version` key.

docker-compose.yml

@@ -1,5 +1,3 @@
-version: '3'
-
 networks:
   main:
     external: true
@@ -48,8 +46,9 @@ services:
       - |
         npm i -g pnpm
         cd /app
-        pnpm install --production
+        pnpm install --frozen-lockfile
         sleep 10
         rm -f .env
         pnpm run build
+        pnpm prune --prod
         pnpm run start