feat(deploy): dockerize web app for portainer git-stack deploy behind external traefik

Add root Dockerfile (standalone Next output, multi-stage pnpm build), drop
in-stack caddy in favor of publishing web's port for an external traefik
LXC (file-provider dynamic config included), and document the portainer
deploy flow.

Also fixes issues that blocked any production build: a bad auth-client
type cast, the ai SDK's mimeType->mediaType rename, an implicit-any
callback param, and push.ts eagerly calling webpush.setVapidDetails at
module import time (which crashed page-data collection whenever VAPID
env vars weren't present at build) — now lazily configured on first send.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/lib/ai/features/import-photo.ts

@@ -49,7 +49,7 @@ export async function importFromPhoto(
       {
         role: "user",
         content: [
-          { type: "image", image: imageBase64, mimeType },
+          { type: "image", image: imageBase64, mediaType: mimeType },
           { type: "text", text: "Extract the complete recipe from this image." },
         ],
       },