The Anthropic Messages API rejects tool IDs that don't match
`^[a-zA-Z0-9_-]+$` with a 400 error. Tool IDs originating from other
providers or restored multi-turn sessions can contain invalid
characters (pipes, dots). Add a deterministic _sanitize_tool_id() and
apply it to both the tool_use id and the matching tool_result
tool_use_id so the pair stays consistent.