Wg/plat/init agent file (#843)

Alias AGENT.md to CLAUDE.md

### Checklist

- [ ] Follow the [manual testing
process](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/TEST.md)
- [ ] Update
[changelog](https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/main/charts/sourcegraph/CHANGELOG.md)
- [ ] Update [Kubernetes update
doc](https://docs.sourcegraph.com/admin/updates/kubernetes)

### Test plan

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Author: DaedalusG

CLAUDE.md

@@ -0,0 +1 @@
+AGENTS.md