v1.7.0 Devin: package deterministic CLI and hosted transports

[jeffhuber]

Part of #1096.

Goal

Package deterministic Devin CLI and hosted transports for Operator use rather than treating Devin as a bespoke campaign-only participant.

Scope

• Versioned work-order/result contract shared by CLI and hosted transport.
• Repository-scope preflight, deterministic dispatch, polling, cancellation, timeout, and uncertain-response reconciliation.
• Isolated credentials, bounded concurrency/spend, and privacy-safe result extraction.
• Builder and reviewer invocation surfaces; no automatic authority promotion.

Acceptance criteria

• CLI and hosted transports produce the same normalized metadata-only result envelope.
• Repository access is verified before paid or mutating dispatch.
• Duplicate dispatch and uncertain completion cannot create two deliveries.
• Auth, quota, timeout, malformed result, cancellation, and restart fixtures fail closed.
• Public docs provide the supported setup and doctor checks without exposing credentials.

Code Mower delivery

One focused transport PR, preferably built with a bounded Devin lane and reviewed by an independent currently qualified reviewer. Building the adapter does not itself qualify Devin for orchestration or merge review.