feat: add target config to resolve-pull-request-review-thread

[strawgate]

Request

Add target, target-repo, and allowed-repos support to resolve-pull-request-review-thread, matching other safe-outputs like add-comment and create-pull-request.

Context

SafeOutputTargetConfig was present in the initial implementation (53cad0d) but intentionally removed in cleanup (9b134b9) before #15668 merged, scoping resolution to the triggering PR only.

This limits use cases where an agent needs to resolve review threads on a PR in a different repository (e.g., cross-repo workflows).

Current behavior

resolve-pull-request-review-thread only accepts max. The JS handler validates threads belong to the triggering PR.

Desired behavior

Support target, target-repo, and allowed-repos fields consistent with other safe-outputs, allowing cross-repo thread resolution.