build(website): Dockerfile + production start script for Coolify

Make the marketing site deployable standalone from apps/website (the repo
has no root package.json, so the build must run in this subdir — set Base
Directory to apps/website in Coolify).

- Add a multi-stage Dockerfile (pnpm build -> node .output/server/index.mjs,
  port 3000, NUXT_PUBLIC_SITE_URL default) + .dockerignore.
- Add a "start" script for the Nixpacks path (Nuxt SSR has no default start).
- Guard the bind-mount-only /shared-packages components dir with existsSync
  so standalone builds don't warn on the missing path (the site uses no
  shared component).

apps/website/Dockerfile

@@ -0,0 +1,25 @@
+# Production image for the dezky marketing site (Nuxt 4 SSR).
+# Build context = this directory (apps/website). In Coolify set the build pack
+# to "Dockerfile" and Base Directory to apps/website.
+# syntax=docker/dockerfile:1
+
+FROM node:22-alpine AS build
+WORKDIR /app
+RUN corepack enable
+# Install deps first for layer caching (pnpm version comes from packageManager).
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile
+COPY . .
+RUN pnpm build
+
+FROM node:22-alpine AS runtime
+WORKDIR /app
+ENV NODE_ENV=production
+ENV HOST=0.0.0.0
+ENV PORT=3000
+# Absolute canonical / OG / sitemap URLs. Override in Coolify if the domain
+# differs (e.g. a staging URL).
+ENV NUXT_PUBLIC_SITE_URL=https://dezky.eu
+COPY --from=build /app/.output ./.output
+EXPOSE 3000
+CMD ["node", ".output/server/index.mjs"]