Fix Docker build: canvas native compile and Vite heap OOM on node:20-slim

[Copilot]

docker compose up --build failed in the frontend-builder stage: canvas (node-gyp rebuild) had no native toolchain or Cairo headers on node:20-slim, and the Vite build hit JavaScript heap out of memory against Node's ~2 GB default heap regardless of Docker memory.

Changes

• Dockerfile — canvas build deps: install python3 make g++ pkg-config and Cairo/Pango/JPEG/GIF/RSVG dev libraries before yarn install so the native module compiles.
• Dockerfile — heap limit: add ARG NODE_HEAP_MB=8192 and ENV NODE_OPTIONS=--max-old-space-size=${NODE_HEAP_MB} before yarn build, overridable per build.
• docker-compose.yml: surface NODE_HEAP_MB: "8192" under build.args.
• yarn.lock — frozen-lockfile blocker: realign the four @tiptap/extension-table* keys from ^3.23.6 to ^3.22.2 to match package.json, keeping the existing 3.23.6 resolutions. Without this, yarn install --frozen-lockfile aborts before reaching the canvas/build steps.

RUN apt-get update && apt-get install -y --no-install-recommends \
        python3 make g++ pkg-config \
        libcairo2-dev libjpeg-dev libpango1.0-dev libgif-dev librsvg2-dev \
    && rm -rf /var/lib/apt/lists/*

ARG NODE_HEAP_MB=8192
ENV NODE_OPTIONS=--max-old-space-size=${NODE_HEAP_MB}

The yarn.lock realignment is intentionally limited to key strings (no version bumps, no registry/URL churn) to keep the dependency tree byte-identical aside from the range match.