The takedown script previously treated any nonempty `ALL_VERSIONS`
value, including `false`, as permission to delete every version. Require
exactly `true` when the variable is set, and reject other values before
sending a request.
Enable strict shell error handling in the auth helper so a failed
identity-token command stops execution before exchanging an empty token.
Validation: `bash -n` and `git diff --check` passed. Mocked command
checks confirmed that `false`, `1`, and `TRUE` are rejected before
network access, and that identity-token retrieval failure stops before
the token exchange. The updated scripts also completed the authorized
takedown associated with #1563; public API reads confirmed the deleted
record and removal from default results.
739b70e8bc