[vkalapov]

Description:

Enriches the Operation error response with a machine-readable failureReason
object so API consumers can act on errors programmatically without parsing
free-text messages.

What changes:

• FailureReason model added: code (enum: CONTENT_VALIDATION_ERROR,
  MODULE_STARTUP_FAILURE, SERVICE_OPERATION_FAILURE,
  CF_API_UNAVAILABLE, QUOTA_EXCEEDED, INTERNAL_ERROR), retryable
  (bool), summary (string).
• Operation gains a nullable failureReason field.
• OperationInErrorStateHandler classifies the root-cause exception and
  populates FailureReason before persisting the operation.
• OperationsHelper extended to carry the failure reason through to the
  response.

Design choices:

• Classification is conservative: unrecognised exceptions map to
  INTERNAL_ERROR / retryable: false rather than guessing.
• summary is intentionally short (one sentence) — full detail remains in
  the messages array.

Issue:

LMCROSSITXSADEPLOY-3718