Function write 

pub fn write(path: &Path, consent: &Consent) -> Result<(), TelemetryError>

Write the consent file. Parent directories are created on demand. The write is not atomic at v0.4 — callers concerned about torn writes implement their own staging on top.

Errors

• TelemetryError::Io for filesystem failures (parent-dir creation, file write).
• TelemetryError::Serde for serialisation failures.