chore: update tailscale/github-action to v4

https://claude.ai/code/session_016uoaNn7tWACKwy6BgpDaRF

Author: claude

.github/workflows/deploy.yml

@@ -48,7 +48,7 @@ jobs:
                     labels: ${{ steps.meta.outputs.labels }}
 
             -   name: Join Tailscale network
-                uses: tailscale/github-action@v2
+                uses: tailscale/github-action@v4
                 with:
                     oauth-client-id: ${{ secrets.TS_OAUTH_CLIENT_ID }}
                     oauth-secret: ${{ secrets.TS_OAUTH_CLIENT_SECRET }}