fix: copy better-sqlite3 native bindings to Docker runtime stage

The .node binary wasn't being copied to .output, causing 'Could not locate
the bindings file' error at runtime.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -12,6 +12,7 @@ ENV NODE_ENV=production
 WORKDIR /app
 RUN mkdir -p /data && chown node:node /data
 COPY --from=build /app/.output ./.output
+COPY --from=build /app/node_modules/better-sqlite3/build ./.output/server/node_modules/better-sqlite3/build
 USER node
 EXPOSE 3000
 HEALTHCHECK --interval=30s --timeout=5s --retries=3 --start-period=15s \