fix: upgrade npm in publish workflow for OIDC support

npm >=11.5.1 required for Trusted Publishing. Actions runner ships 10.8.2.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: BrainSlugs83

.github/workflows/publish.yml

@@ -18,6 +18,7 @@ jobs:
           node-version: 22
           registry-url: https://registry.npmjs.org
 
+      - run: npm install -g npm@latest
       - run: npm ci
 
       # Set package version from release tag (e.g. v1.6.0 → 1.6.0)