DO_NOT_TRACK: one env var to silence telemetry across every CLI tool

A new proposal pushes for a single standard environment variable, DO_NOT_TRACK=1, that any CLI, SDK, or framework should honor as a blanket opt-out from analytics, crash reporting, usage stats, and other non-essential phone-home behavior. The pitch is purely about reducing friction: today every tool ships its own flag, config key, or undocumented incantation to disable telemetry, and users have no realistic way to keep up.

The model mirrors the older DO_NOT_TRACK browser header but targets local developer tooling, where opt-out telemetry has quietly become the norm. Authors are asked to treat the variable as authoritative alongside existing mechanisms, and to reconsider opt-out defaults entirely in favor of opt-in. Adoption is the only thing that matters here — the spec is trivial; the question is whether enough tool maintainers respect it to make exporting one line in a shell rc file actually meaningful.