feat(safe-outputs): allow model-selected PR reviewers

[Copilot]

Summary

Model-selected reviewers need the PR created by the same run, but Azure DevOps assigns its numeric ID only during SafeOutputs execution. Rather than making reviewer selection a special inline field on create-pull-request, this change adds composable temporary PR references:

• create-pull-request returns and persists a server-generated #aw_... temporary ID.
• Every update-pr operation accepts either a numeric PR ID or a same-job temporary ID.
• Temporary references retain the exact organization, project, and repository target, including cross-organization routing.
• Model-selected reviewers remain an update-pr add-reviewers operation with default-deny allowed-reviewers and a separate max-reviewers limit.
• Reviewer identities require an unambiguous case-insensitive exact email, account, display-name, or GUID match; fuzzy first-result selection is removed.
• Reviewer resolution and API failures return structured warnings with added and failed arrays, while policy and reference failures remain hard failures.
• Static operator-configured create-pull-request.reviewers remain unchanged.

safe-outputs:
  create-pull-request: {}
  update-pr:
    allowed-operations:
      - add-reviewers
    allowed-reviewers:
      - user@example.com
    max-reviewers: 3
    max: 2

Temporary IDs resolve in NDJSON proposal order and only within one SafeOutputs job. Automatic and manually reviewed outputs run in separate jobs and therefore cannot share temporary references.

Test plan

• Verify create-PR MCP responses return and persist generated temporary IDs.
• Verify create-PR input excludes internal temporary IDs and inline model reviewer fields.
• Verify numeric, quoted numeric, and temporary PR reference parsing and routing.
• Verify exact cross-organization target retention and repository mismatch rejection.
• Verify default-deny reviewer policy, wildcard opt-in, limits, and deduplication.
• Verify exact identity matching rejects fuzzy and ambiguous results.
• Verify partial and total reviewer failures produce structured warnings.
• Verify ordered executor NDJSON creates a PR, registers its temporary ID, then resolves it in a following update-pr request.
• Add the same create→update temporary-ID handoff to the deterministic Azure DevOps executor E2E suite.
• Run cargo test --all-targets.
• Run cargo clippy --all-targets.

• Fixes [agent-issue]: Allow model-selected reviewers in create-pull-request #2090

[azure-pipelines]

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