Classify private-safe account-facts publish failures

[Pigbibi]

Purpose

Classify the existing account-facts POST failure without printing private response bodies, URLs, tokens, identifiers or exception messages.

Changes

• Only known receiver status/code pairs become fixed diagnostic labels.
• Response reads stay bounded to 4097 bytes with a 4096-byte parse limit.
• Network, timeout and invalid acknowledgements get fixed stop codes.
• No retry, redirect, payload validation or success semantics change.

Validation

Synthetic cases cover known HTTP failures, unexpected/private/oversized response bodies, malformed acknowledgements and transport failures. Runtime publishing is still stopped pending readback of the earlier write outcome.