fix(dev): support root bind mounts and LAN Vite access

Keep the dev container as root for s6 init so composer can create
vendor/ on root-owned mounts, then chown writable paths to www-data.
Move init-setup into a shell script and expose VITE_HOST/PORT for
remote HMR (LAN/Tailscale) with Vite listening on 0.0.0.0.

package.json

@@ -3,7 +3,7 @@
     "private": true,
     "type": "module",
     "scripts": {
-        "dev": "vite",
+        "dev": "vite --host",
         "build": "vite build"
     },
     "devDependencies": {