Prototype opt‑in auto‑update for Insiders builds

[kristenwomack]

Description

Prototype opt‑in auto‑update behavior for Insiders builds only. This is an experimental implementation intended to validate technical feasibility, failure modes, and user experience before expanding to Stable users.

In scope

• Opt‑in auto‑update for Insiders channel
• Ability to pin versions or opt out
• Safe failure behavior (no silent breakage)
• Internal testing with Microsoft users

Out of scope

• Default auto‑update for Stable users
• Broad customer rollout

Acceptance criteria

• Auto‑update is explicitly opt‑in
• Only applies to Insiders builds
• Users can opt out or pin versions
• Failures are surfaced clearly and safely
• Internal feedback is collected

[spboyer]

Closing — opt-in auto-update for Insiders/daily builds was implemented by PR #6942 (azd update command with channel management). Follow-up PRs #7011 (channel inference from binary version) and #7012 (macOS binary replacement fix) further refined the feature.