Speed up Docusaurus build (#146)

* Speed up Docusaurus build with Rspack, image compression, and CI caching

- Add @docusaurus/faster for Rspack bundler, SWC transpilation/minification,
  Lightning CSS, MDX cross-compiler cache, and multi-threaded SSG
- Limit dev server to current version only for faster local development
- Remove babel.config.js (replaced by SWC)
- Add Docusaurus build cache step in CI workflow
- Upgrade Node from 20 to 24 in CI
- Compress 138 large PNG images with pngquant (65-80% quality)

* Compress PNG images over 100KB with pngquant

330 additional images compressed (quality 65-80%, skip-if-larger).
Reduces repository size and speeds up checkout, CI, and deployment.

* Pin actions/cache to full commit SHA

Required by org policy that all actions must be pinned to a
full-length commit SHA.

* Trigger CI

* Reduce Node heap to 4 GB to prevent OOM on CI runners

Rspack (which replaced webpack) runs as native Rust code outside the
Node heap. With 6 GB allocated to Node, peak memory reached 8.3 GB
total (Node + Rspack native), exceeding the 7 GB runner limit and
causing the Linux OOM killer to terminate the build. Setting the heap
to 4 GB leaves ~3 GB for Rspack and the OS.

* Add swap space to CI runner to prevent OOM kills

The Rspack build peaks at ~8 GB, exceeding the 7 GB runner limit.
Adding 10 GB swap prevents the Linux OOM killer from terminating the
build process.

* Fix swap setup: resize existing swapfile instead of creating new one

GitHub runners already have a 4 GB /swapfile in use. Disable it first,
then recreate at 14 GB to give enough headroom for the Rspack build.

* Restore Node heap to 6 GB now that swap prevents OOM kills

With 14 GB swap as safety net, the 6 GB heap allows V8 to GC less
aggressively, improving build performance. Brief memory peaks above
7 GB will use swap instead of crashing.

Author: Miggets7

.github/workflows/ci_cd.yml

@@ -15,27 +15,48 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  # Hosted GitHub runners have 7 GB of memory available, let's use 6 GB
+  # Hosted GitHub runners have 7 GB of memory available, swap handles brief peaks above this
   NODE_OPTIONS: --max-old-space-size=6144
 
 jobs:
   build:
     name: Build
     runs-on: ubuntu-latest
     steps:
+      - name: Add swap space
+        run: |
+          # Resize existing swap from default 4 GB to 14 GB
+          sudo swapoff /swapfile || true
+          sudo rm -f /swapfile
+          sudo fallocate -l 14G /swapfile
+          sudo chmod 600 /swapfile
+          sudo mkswap /swapfile
+          sudo swapon /swapfile
+          free -h
+
       - name: Checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
       - name: Setup Node
         uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
-          node-version: '20'
+          node-version: '24'
           cache: 'yarn'
           cache-dependency-path: yarn.lock
 
       - name: Install dependencies
         run: yarn install --immutable
 
+      - name: Cache Docusaurus build
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+        with:
+          path: |
+            .docusaurus
+            node_modules/.cache
+          key: docusaurus-${{ runner.os }}-${{ hashFiles('yarn.lock', 'docusaurus.config.ts', 'versions.json') }}
+          restore-keys: |
+            docusaurus-${{ runner.os }}-
+
       - name: Build
         run: yarn build