ci: bump checkout/setup-node/upload+download-artifact v4 → v5

The v4 actions target Node.js 20, which GitHub now force-runs on Node 24
and flags as deprecated. Bump all four across every workflow to v5 (their
native Node-24 line) to clear the warning. Mechanical version-only change;
upload/download-artifact stay on matching majors as required.

Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01DwbE3uTiFaKRNjx5vP2muV

.github/workflows/nsite-archive.yml

@@ -26,9 +26,9 @@ jobs:
   archive:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
           node-version: 22
           cache: npm
@@ -46,7 +46,7 @@ jobs:
       # `path: dist` stores the site files at the artifact root (index.html at top),
       # so the downloaded .zip extracts straight to the nsite site directory.
       - name: Upload site archive
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: bitvid-site-${{ github.ref_name }}-${{ steps.vars.outputs.sha }}
           path: dist
@@ -64,9 +64,9 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
 
-      - uses: actions/setup-node@v4
+      - uses: actions/setup-node@v5
         with:
           node-version: 22
           cache: npm