docs: rebrand README + add Docker and bare-metal deploy

- Rewrite README with RetroBlog branding, config table, and two deploy
  paths (Docker Compose + bare-metal/systemd).
- Enable Next.js standalone output for slim runtime images.
- Add multi-stage Dockerfile (builds better-sqlite3 natively, runs as
  non-root, persists /app/data), docker-compose.yml, and .dockerignore.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,45 @@
+# syntax=docker/dockerfile:1
+
+# ---- deps: install node_modules (native build tools for better-sqlite3) ----
+FROM node:22-bookworm-slim AS deps
+WORKDIR /app
+RUN apt-get update && apt-get install -y --no-install-recommends \
+      python3 make g++ \
+    && rm -rf /var/lib/apt/lists/*
+RUN corepack enable
+COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
+RUN pnpm install --frozen-lockfile
+
+# ---- builder: compile the Next.js standalone server ----
+FROM node:22-bookworm-slim AS builder
+WORKDIR /app
+RUN corepack enable
+COPY --from=deps /app/node_modules ./node_modules
+COPY . .
+ENV NEXT_TELEMETRY_DISABLED=1
+RUN pnpm build
+
+# ---- runner: minimal runtime image ----
+FROM node:22-bookworm-slim AS runner
+WORKDIR /app
+ENV NODE_ENV=production \
+    NEXT_TELEMETRY_DISABLED=1 \
+    PORT=3000 \
+    HOSTNAME=0.0.0.0
+
+# Non-root user; owns the data volume so SQLite can write.
+RUN addgroup --system --gid 1001 nodejs \
+    && adduser --system --uid 1001 nextjs
+
+# Standalone output bundles the traced node_modules (incl. the better-sqlite3
+# native binary), so no install/rebuild is needed here.
+COPY --from=builder /app/.next/standalone ./
+COPY --from=builder /app/.next/static ./.next/static
+COPY --from=builder /app/public ./public
+
+RUN mkdir -p /app/data && chown -R nextjs:nodejs /app/data
+VOLUME ["/app/data"]
+USER nextjs
+
+EXPOSE 3000
+CMD ["node", "server.js"]