fix: Add packages write permission to publish workflow

- Add permissions for contents:write and packages:write
- Fixes 403 Forbidden error when publishing to GitHub Packages
- GITHUB_TOKEN now has required permissions for package publishing

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

Co-Authored-By: Claude <[email protected]>

Author: datlogysoftware

.github/workflows/nuget-publish.yml

@@ -19,6 +19,9 @@ jobs:
   publish:
     name: Build and Publish NuGet Packages
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      packages: write
 
     steps:
     - name: Checkout code