Include Node version in CI setup cache key [FFESUPPORT-731] (#120)

The composite setup action caches `**/node_modules` keyed on OS +
`yarn.lock` hash only. If a `node_modules` cache built under a
different Node version were restored, packages with native bindings
could load mismatched ABI binaries — and because the cache-hit path
skips the install step, deps wouldn't get rebuilt.

Capture the resolved Node version (`node -v`) into a step output, then
include it in both the primary cache key and the `restore-keys` prefix.
That way, bumping Node automatically busts the cache instead of relying
on lockfile churn to do it incidentally.

Stays with `actions/setup-node@v3` and `actions/cache@v3` — this is the
minimal-change variant. Caching Yarn's download cache instead of
`node_modules` would be the more robust pattern, but that's a bigger
restructure for a separate ticket if we want it.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: aarsilv

.github/actions/setup/action.yml

@@ -9,15 +9,20 @@ runs:
       with:
         node-version: '20.x'  # Specify the Node.js version directly here
 
+    - name: Resolve installed Node version
+      id: node-info
+      run: echo "version=$(node -v)" >> "$GITHUB_OUTPUT"
+      shell: bash
+
     - name: Cache dependencies
       id: yarn-cache
       uses: actions/cache@v3
       with:
         path: |
           **/node_modules
-        key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+        key: ${{ runner.os }}-node-${{ steps.node-info.outputs.version }}-yarn-${{ hashFiles('**/yarn.lock') }}
         restore-keys: |
-          ${{ runner.os }}-yarn-
+          ${{ runner.os }}-node-${{ steps.node-info.outputs.version }}-yarn-
 
     - name: Install dependencies
       if: steps.yarn-cache.outputs.cache-hit != 'true'