fix(workflows): update add-pr-to-project to use PROJECT_ACCESS_TOKEN

The default GITHUB_TOKEN doesn't have permissions to access organization-level
GitHub Projects (Projects V2). This change updates the workflow to use a
personal access token with the necessary project permissions.

To fix the "Resource not accessible by integration" error, you need to:
1. Create a PAT with 'repo' and 'project' scopes
2. Add it as PROJECT_ACCESS_TOKEN in repository secrets
3. Re-run the failed workflow

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: ryanrozich

.github/workflows/add-pr-to-project.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Add PR to Project
         uses: actions/github-script@v7
         with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
+          github-token: ${{ secrets.PROJECT_ACCESS_TOKEN }}
           script: |
             const pr = context.payload.pull_request;
             console.log(`Adding PR #${pr.number} to project`);