One script for end-to-end deployment on substrate

[wjjclaud]

Summary

• Deploy both the Agent Substrate control plane and AX from this repo with a single script (hack/install-ax.sh) and a single self-contained guide (manifests/README.md).
• The substrate version is handled automatically from the go.mod pin — no more manually aligning a substrate checkout / cluster version. Uses don't need to clone and maintain a substrate repo themselves.

What's changed

hack/install-ax.sh:

• --create-cluster / --delete-cluster — one-time GCP provisioning / teardown (wraps substrate's tools/setup-gcp and hack/teardown.sh).
• --deploy-ate-system / --delete-ate-system — substrate control plane at the pinned version (wraps substrate's hack/install-ate.sh).
• --deploy-ax / --delete-ax — AX server + harness (renamed from --deploy-ax-server / --delete-ax-server).
• --delete-all — tear down AX + substrate control plane (in-cluster).

Others

• Rename Env var BUCKET_NAME → AX_SNAPSHOTS_BUCKET Fix Rename BUCKET_NAME to AX_SNAPSHOTS_BUCKET #219.
• Bump substrate version.
• More detailed instructions for end to end deployment in README.

Tested

Deploy and run antigravity on substrate.

[rakyll]

IMHO we shouldn't do this. We really don't want AX to be responsible of maintaining Substrate deployment. Also the lifecycle of AX and Substrate deployments are different.

Substrate will be deployed once and updated very rarely. AX may be deployed many times against the same cluster under different namespaces.

cc @dberkov