ci: authenticate npm's private @plugpress/ui fetch in the release build

npm ci resolves @plugpress/ui from the private plugpressco/plugpress-ui
repo, which the runner's default token cannot read — every tagged
release build died before building a zip. Route github.com fetches
through SADDLE_REPO_TOKEN (the same org PAT Pro's CI expects; add it as
an org secret to fix both repos at once).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MdDtwAWL2u1oDKq5tNANT6

Author: ifahimreza

.github/workflows/release.yml

@@ -40,6 +40,12 @@ jobs:
           node-version: '20'
           cache: npm
 
+      - name: Grant access to private packages
+        # @plugpress/ui resolves to the private plugpressco/plugpress-ui repo;
+        # the default GITHUB_TOKEN cannot read it. SADDLE_REPO_TOKEN is the
+        # same org PAT Pro's CI uses to check out private repos.
+        run: git config --global url."https://x-access-token:${{ secrets.SADDLE_REPO_TOKEN }}@github.com/".insteadOf "https://github.com/"
+
       - name: Install build tooling
         run: npm ci