ci(loader): opt v4 actions into Node 24 runtime ahead of forced flip

GitHub deprecated Node 20 for JavaScript actions on 2025-09-19; v4 of
checkout / setup-java / cache / upload-artifact and ilammy/msvc-dev-cmd
still ship a Node 20 binary in action.yml. Set
FORCE_JAVASCRIPT_ACTIONS_TO_NODE24=true at job scope so the runner
executes them under Node 24 now - silences the deprecation warning and
removes a 2026-06-02 surprise when the default flips.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/workflows/build-loader.yml

@@ -31,6 +31,13 @@ jobs:
       # populate ${VCPKG_ROOT}/archives, which actions/cache then
       # snapshots along with installed/.
       VCPKG_BINARY_SOURCES: "clear;files,${{ github.workspace }}\\vcpkg-archives,readwrite"
+      # Opt every JavaScript action into the Node.js 24 runtime ahead of the
+      # 2026-06-02 forced switchover. The v4 / v1 pins below all still ship
+      # a Node 20 binary in their action.yml, and GitHub deprecated Node 20
+      # on 2025-09-19; setting this flag makes the runner execute them under
+      # Node 24 regardless, which silences the deprecation warning and
+      # de-risks the upcoming default flip.
+      FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: "true"
 
     steps:
       - name: Checkout