init: info-canicule MVP (Vigilance + climato + conseils)

Astro 5 SSR + ioredis cache Valkey, déployable sur shared-net.
- Vigilance temps réel via Opendatasoft (no-auth, LOv2)
- Carte SVG des 96 départements (gregoiredavid/france-geojson)
- Climato T° 30j par dept (CSV.GZ Météo France, cache 24h)
- Conseils officiels par phénomène (7 types Vigilance)
- /api/health (UptimeRobot) + /api/vigilance (JSON public CORS *)
- Dockerfile multi-stage, CI Forgejo deploy.yml (pattern Reteno)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,31 @@
+# syntax=docker/dockerfile:1.7
+
+FROM node:22-alpine AS deps
+WORKDIR /app
+RUN corepack enable
+COPY package.json pnpm-lock.yaml* ./
+RUN --mount=type=cache,target=/root/.local/share/pnpm/store \
+    pnpm install --frozen-lockfile
+
+FROM node:22-alpine AS build
+WORKDIR /app
+RUN corepack enable
+ENV NODE_ENV=production
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+RUN pnpm build
+
+FROM node:22-alpine AS runtime
+WORKDIR /app
+ENV NODE_ENV=production \
+    PORT=4321 \
+    HOST=0.0.0.0
+RUN addgroup -S app && adduser -S app -G app
+COPY --from=build --chown=app:app /app/dist ./dist
+COPY --from=build --chown=app:app /app/node_modules ./node_modules
+COPY --from=build --chown=app:app /app/package.json ./
+USER app
+EXPOSE 4321
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 \
+  CMD wget -qO- http://127.0.0.1:4321/api/health || exit 1
+CMD ["node", "./dist/server/entry.mjs"]