Add Docker deployment config and v3.02 firmware docs

Deployment: Dockerfile (multi-stage dev/prod with Caddy static
serving), docker-compose.yml (caddy-docker-proxy labels),
Caddyfile, Makefile, .dockerignore.

Docs: v3.02 firmware page, v3.01 updates.

site/Dockerfile

@@ -0,0 +1,24 @@
+# ── base: shared dependency install ──────────────────────────────
+FROM node:20-slim AS base
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY . .
+
+# ── dev: Astro dev server with HMR ─────────────────────────────
+FROM base AS dev
+ENV HOST=0.0.0.0
+EXPOSE 4321
+CMD ["npx", "astro", "dev", "--host", "0.0.0.0", "--port", "4321"]
+
+# ── build: static site generation ───────────────────────────────
+FROM base AS build
+RUN npx astro build
+
+# ── prod: Caddy serving static files ───────────────────────────
+FROM caddy:2-alpine AS prod
+COPY Caddyfile /etc/caddy/Caddyfile
+COPY --from=build /app/dist /srv
+EXPOSE 80
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+  CMD wget -qO- http://127.0.0.1:80/health || exit 1