✨(frontend) Introduce frontend Docker image

Inspired by the Docker images from numerique-gouv/people and numerique-gouv/impress
(see commit 1a3b396 in the "people" repository).

Due to the lack of a certified cold storage solution (e.g., S3) for serving static files,
we've containerized the frontend as a temporary deployment solution.

Vite.js static output is served using an Nginx reverse proxy.

I am not quite sure of this commit, please @manuhabitela could you review how I exposed
the static build from vite in my Nginx server? and do the appriopriate fix if necessary.

src/frontend/Dockerfile

@@ -0,0 +1,50 @@
+FROM node:20-alpine as frontend-deps
+
+WORKDIR /home/frontend/
+
+COPY ./src/frontend/package.json ./package.json
+COPY ./src/frontend/package-lock.json ./package-lock.json
+
+RUN npm ci
+
+COPY .dockerignore ./.dockerignore
+COPY ./src/frontend/ .
+
+### ---- Front-end builder image ----
+FROM frontend-deps as meet
+
+WORKDIR /home/frontend
+
+FROM frontend-deps as meet-dev
+
+WORKDIR /home/frontend
+
+EXPOSE 3000
+
+CMD [ "npm", "run", "dev"]
+
+# Tilt will rebuild Meet target so, we dissociate meet and meet-builder
+# to avoid rebuilding the app at every changes.
+FROM meet as meet-builder
+
+WORKDIR /home/frontend
+
+RUN npm run build
+
+# ---- Front-end image ----
+FROM nginxinc/nginx-unprivileged:1.25 as frontend-production
+
+# Un-privileged user running the application
+ARG DOCKER_USER
+USER ${DOCKER_USER}
+
+COPY --from=meet-builder \
+    /home/frontend/dist \
+    /usr/share/nginx/html
+
+COPY ./src/frontend/default.conf /etc/nginx/conf.d
+COPY ./docker/files/usr/local/bin/entrypoint /usr/local/bin/entrypoint
+
+ENTRYPOINT [ "/usr/local/bin/entrypoint" ]
+
+CMD ["nginx", "-g", "daemon off;"]

src/frontend/default.conf

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+server {
+  listen 8080;
+  server_name localhost;
+
+  root /usr/share/nginx/html;
+
+  location / {
+      try_files $uri index.html $uri/ =404;
+  }
+
+  error_page 404 /404.html;
+  location = /404.html {
+      internal;
+  }
+}