feat: add Docker support with self-hosted and hosted presets

Multi-stage Dockerfile (Node 22 Alpine), docker-compose for self-hosted
and hosted deployments, CI workflow for GHCR publishing, runtime env var
substitution, and cron sidecar with supercronic.

Aligns hosted extension preset with dev config (enable-banking,
ai-categorization, ai-chat, email).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,63 @@
+# ── Stage 1: Base ──
+FROM node:22-alpine AS base
+RUN apk add --no-cache libc6-compat
+
+# ── Stage 2: Dependencies ──
+FROM base AS deps
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+
+# ── Stage 3: Builder ──
+FROM base AS builder
+WORKDIR /app
+
+ARG EXTENSIONS_PRESET=self-hosted
+
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+
+# Apply extension preset (must happen before build — prebuild hook
+# runs setup:extensions which reads extensions.config.json)
+COPY docker/extensions.${EXTENSIONS_PRESET}.json ./extensions.config.json
+
+# Build with placeholder sentinel values for NEXT_PUBLIC_* vars.
+# These get replaced at runtime by docker-entrypoint.sh so the image
+# is generic and reusable across different Supabase projects.
+ENV NEXT_PUBLIC_SUPABASE_URL=__NEXT_PUBLIC_SUPABASE_URL__
+ENV NEXT_PUBLIC_SUPABASE_ANON_KEY=__NEXT_PUBLIC_SUPABASE_ANON_KEY__
+ENV NEXT_PUBLIC_APP_URL=__NEXT_PUBLIC_APP_URL__
+ENV NEXT_PUBLIC_VAPID_PUBLIC_KEY=__NEXT_PUBLIC_VAPID_PUBLIC_KEY__
+
+ENV NEXT_TELEMETRY_DISABLED=1
+
+RUN npm run build
+
+# ── Stage 4: Runner ──
+FROM node:22-alpine AS runner
+WORKDIR /app
+
+RUN apk add --no-cache curl
+
+ENV NODE_ENV=production
+ENV NEXT_TELEMETRY_DISABLED=1
+
+RUN addgroup --system --gid 1001 nodejs && \
+    adduser --system --uid 1001 nextjs
+
+# Copy standalone output
+COPY --from=builder /app/public ./public
+COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
+COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
+
+# Copy entrypoint script
+COPY --chmod=755 docker-entrypoint.sh ./docker-entrypoint.sh
+
+USER nextjs
+
+EXPOSE 3000
+ENV PORT=3000
+ENV HOSTNAME=0.0.0.0
+
+ENTRYPOINT ["./docker-entrypoint.sh"]
+CMD ["node", "server.js"]