[shin0343]

What's changing and why?

hyp list cluster-stack and HpClusterStack.list() return every CloudFormation stack in the account and Region, not only HyperPod-related stacks. The CLI help text, output header, and documentation incorrectly described the results as HyperPod-only (see #348).

This PR implements the minimal short-term fix suggested in the issue:

• Corrects the CLI help text and usage examples
• Updates the SDK docstring to document the actual behavior
• Changes the output header from HyperPod Cluster Stacks to CloudFormation Stacks
• Aligns the README, Read the Docs, and example notebooks
• Fixes the invalid help example hyp list hyp-cluster → hyp list cluster-stack
• Adds regression tests covering mixed HyperPod and unrelated stacks, plus help/behavior consistency

Tag-based filtering is intentionally not included:

• CloudFormation ListStacks does not return stack tags
• CLI-created stacks only carry user-provided tags, while Console-created and legacy stacks may be untagged
• Stack-name-prefix filtering would miss valid HyperPod stacks and would silently change existing behavior

Existing behavior is unchanged: --region, --status, pagination, and the default exclusion of DELETE_COMPLETE stacks all work as before.

Before/After UX

Before:

$ hyp list cluster-stack
📋 HyperPod Cluster Stacks (2 found)
...

Help text claimed: "List all HyperPod cluster stacks."

After:

$ hyp list cluster-stack
📋 CloudFormation Stacks (2 found)
...

Help text now says: "List CloudFormation stacks in the current AWS account and Region." and explicitly notes that results are not filtered to HyperPod stacks.

How was this change tested?

• tox -e unit (Python 3.11.15): 1249 passed, 19 warnings, coverage 80.11%
• Targeted regression tests:
  pytest test/unit_tests/cli/test_cluster_stack.py test/unit_tests/cluster_management/test_hp_cluster_stack.py
  → 64 passed
• Mocked CLI invocation verified that an unrelated CloudFormation stack appears in the output and that region_name and StackStatusFilter are still passed through to CloudFormation
• git diff --check, notebook JSON validation, and a scoped git-secrets scan of the changed files passed

Not run in this environment:

• Integration tests (require real AWS credentials and resources)
• Sphinx documentation build (Sphinx is not installed locally)
• Python 3.8/3.9/3.10 unit tests (only Python 3.11 is available locally)

Are unit tests added?

Yes.

• test_list_cluster_stacks_includes_unrelated_cloudformation_stacks verifies that non-HyperPod stacks are returned and displayed.
• test_list_cluster_stacks_help_describes_all_stacks verifies that the help text no longer claims HyperPod-only results.
• The existing success test now asserts the corrected output header.

Are integration tests added?

No. This change only updates user-facing text, documentation, and unit tests; it does not change AWS API calls or filtering behavior.

Refs #348