Function decap_key_config_snippet 

fn decap_key_config_snippet(decap_key: &DecapKeyBytes) -> Result<String>

Renders decap_key = { ... } as a multi-line inline table (so it can be pasted under a transcryptor or authentication server), wrapping the long base64 fields across lines. The structure is written via toml_writer; only the \-folding - which no TOML serializer does for us - is done here.