Replace deploy skill ACR build run-status polling with a script

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## Summary

Copilot has identified a portion of a skill that is a good candidate for replacement with a script.

The candidate is the **ACR build run-status polling** in the `foundry-agent/deploy` skill (`deploy.md`).

## Candidate description

**ACR build run-status polling (Error Handling)**

When `az acr build` log streaming crashes, the skill recovers by getting the `` and repeatedly calling `az acr task show-run ... --query status` until the run reaches a terminal state. This is a polling loop over a large-output command reduced to a single status field — a natural fit for a script that takes a registry and run id and returns the terminal status.

## Affected file and lines

- [`deploy.md` — Error Handling: ACR build log crash recovery (L467)](https://github.com/microsoft/GitHub-Copilot-for-Azure/blob/164e0cda7b9d75d6e0d64b235d17bd7ff5e2909e/plugin/skills/microsoft-foundry/foundry-agent/deploy/deploy.md#L467)

## Next steps

1. **Evaluate the candidate** — confirm the steps are stable and parameterizable, and that the script captures everything the skill needs.
2. **Create both a bash _and_ a PowerShell version** of the script so the skill works across platforms.
3. **Run integration tests** to verify the scripts behave correctly and the skill still completes end-to-end.

## Background Information

### Why replace regular steps with scripts

Replacing a regular, well-defined series of steps with a script can:

- **Reduce token usage** — the skill no longer needs to spell out each command and parse large command output inline; the agent invokes one script and reads a compact result.
- **Improve reliability** — the logic is written and tested once, instead of being re-derived by the agent on every run.
- **Improve determinism** — the same inputs always produce the same steps and output, removing run-to-run variation.
- **Improve speed of execution** — a single script call replaces multiple round-trips of command generation, execution, and large-output parsing.

### Authoring notes for the scripts

- **Reference scripts with markdown links**, not just a bare path to the script file.
- **Include examples** in the skill showing how to run each script (sample invocation with arguments).
- **Briefly explain what each script does** where it is referenced.
- **The script output should explain what it did**, so the agent and user can understand the result without re-inspecting raw command output.

Start with the ACR build log crash recovery section at deploy.md line 467 and review the existing az acr task show-run status polling steps. Check the repository's script conventions and integration-test setup before creating bash and PowerShell versions. Done means both scripts return the terminal status, deploy.md links to them with examples, and the integration tests confirm the skill still completes end-to-end.

Written by the indexing model from the issue text.