feat(ci): auto-redeploy ci3 dashboard on push to next

[AztecBot]

Adds .github/workflows/ci3-dashboard-deploy.yml so changes under ci3/dashboard/** (and the workflow itself) automatically run ci3/dashboard/deploy.sh after they land on next. Also exposed via workflow_dispatch so the deploy can be triggered manually from the Actions tab without an SSH-capable workstation.

Today the dashboard at https://ci.aztec-labs.com is updated by an operator running ci3/dashboard/deploy.sh locally, which rsyncs the rkapp files to ubuntu@ci.aztec-labs.com and systemctl restart rkapps. That left e.g. PR #23160 (<path:key> route fix for merge-train/* history) stuck waiting for a manual ship after merge.

Mechanics:

• Trigger: push to next with a paths: filter on ci3/dashboard/** so only dashboard-touching merges deploy. workflow_dispatch for manual runs.
• concurrency: { group: ${{ github.workflow }}, cancel-in-progress: false } — at most one deploy in flight, never cancel one mid-rsync/restart.
• Reuses the existing BUILD_INSTANCE_SSH_KEY secret already wired into avm-circuit-inputs.yml / claudebox.yml, decoded to ~/.ssh/build_instance_key exactly the same way.
• ssh-keyscan ci.aztec-labs.com >> ~/.ssh/known_hosts before the script runs so deploy.sh doesn't need editing — keeps the script reusable from a workstation unchanged.

After this lands, the next merge that touches ci3/dashboard/** will redeploy on its own; existing pending fixes can be shipped immediately via the Actions tab's "Run workflow" button without that.

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Created by claudebox · group: slackbot