Audit confirmation-error class and identity consumers for the new wrapper #3331

Draft #3187 intentionally wraps post-commit confirmation failures in ReplicationConfirmationError to protect shared and frozen rejection objects. cause retains the exact original error. Programmatic constructor/identity checks and string error prefixes observe the wrapper; object responses retain the original public code.

Audit consumers that classify confirmation failures by instance, class or text prefix and record the migration to the outcome fields and cause. Preserve protection for shared/frozen causes. The companion documentation already dispatched by the maintainer covers the migration. This records the accepted compatibility follow-up from the independent review of #3187.

This is a pre-release audit of the intentional v5.4/main change; no downstream failing consumer has been demonstrated in this Harper-only worktree.

Review-Deferral: d6a146f7ae8937e6 severity=major category=correctness

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