feat: add container CI/CD workflow

Dockerfile

@@ -1,4 +1,4 @@
-FROM node:24-alpine AS build
+FROM node:24-alpine@sha256:d32cdf619f63fe0471182d08996dd516c6275bb5fd31ae06e55a570bd9e1ad43 AS build
 
 WORKDIR /app
 RUN corepack enable
@@ -9,7 +9,7 @@ RUN pnpm install --frozen-lockfile
 COPY . .
 RUN pnpm build
 
-FROM caddy:2.10.2-alpine
+FROM caddy:2.10.2-alpine@sha256:4c6e91c6ed0e2fa03efd5b44747b625fec79bc9cd06ac5235a779726618e530d
 
 RUN apk add --no-cache jq nodejs
 COPY Caddyfile /etc/caddy/Caddyfile
@@ -19,5 +19,7 @@ COPY --from=build /app/dist-server/edge-tts-server.cjs /usr/local/lib/tjwater-fr
 RUN chmod 755 /usr/local/bin/tjwater-frontend-entrypoint
 
 EXPOSE 80
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD wget --quiet --spider http://127.0.0.1/ || exit 1
 ENTRYPOINT ["/usr/local/bin/tjwater-frontend-entrypoint"]
 CMD ["caddy", "run", "--config", "/etc/caddy/Caddyfile", "--adapter", "caddyfile"]