Fail deployment on hardcoded references to the current namespace

[shangyian]

Summary

When working in a branch namespace (<namespace>.<branch>.<...>), it's possible to write a node query that hardcodes a reference to the current branch namespace instead of using ${prefix}. For example, a metric deployed to myteam.feature_branch that references myteam.feature_branch.transforms.revenue_fact directly.

The change will validate and deploy cleanly while the branch exists, but breaks after merge. Once the branch is merged to main and the temporary branch namespace is cleaned up, the hardcoded reference becomes a dangling pointer to a namespace that no longer exists. The failure only surfaces later, at SQL-request time, with a confusing "cannot find join path" or missing-node error far removed from the actual cause.

Thus, during deployment validation, we should flag any node whose query references a dependency starting with the deployment namespace prefix. Such a reference should always go through ${prefix} so it survives branch merges.

To do this, we added _check_hardcoded_namespace_ref to NodeSpecBulkValidator, where for each dependency in the node's already-computed dependency list, we check whether it starts with deployment_namespace. If so, we mark the node INVALID with an INVALID_NAMESPACE error directing the user to use ${prefix}. Other nodes in the push are unaffected.

This change makes no additional DB queries, so there should be perf degradation for deploying.

Test Plan

Added four unit tests covering: hardcoded self-reference produces the error, cross-namespace references are allowed, the check is skipped when no deployment namespace is set (REST API path), and clean queries produce no error.

• PR has an associated issue: #
• make check passes
• make test shows 100% unit test coverage

Deployment Plan

[netlify]

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