Preserve non-empty candidates in compact agent-task review

[chubes4]

Summary

• preserve the selected task-scoped artifact in compact review projection
• report real candidate size and changed-file evidence instead of an empty no-op
• require an explicit destination before emitting a runnable promotion command

Verification

• cargo fmt --all -- --check
• cargo test --locked -p homeboy-cli commands::agent_task::tests::promotion_review::default_review_is_bounded_and_points_to_full_evidence
• cargo test --locked -p homeboy-cli commands::agent_task::review::tests::compact_apply_candidate_uses_the_selected_task_and_artifact_id
• cargo test --locked -p homeboy-cli commands::agent_task_summary::tests::review_summary_keeps_the_default_compact_apply_candidate

Closes #11982

AI Assistance

OpenAI gpt-5.6-sol via OpenCode implemented, reviewed, and verified this repair under human direction. Chris Huber remains responsible for every line.

[homeboy-ci]

Homeboy Results — homeboy

Lint

✅ review lint — passed

ℹ️ Full options: homeboy self docs commands/lint
ℹ️ Save lint baseline: homeboy review lint homeboy --baseline
Deep dive: homeboy review lint homeboy --changed-since 66a6691

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-lint-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-lint-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31279431897

Audit

⚠️ review audit — no measurement

Deep dive: homeboy review audit homeboy --changed-since 66a6691

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-review-audit-homeboy-fast-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-review-audit-homeboy-fast-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/31279431897

Tooling versions

• Homeboy CLI: homeboy 0.334.0+73c0c6406d15-dirty
• Extension: rust from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: a32e4ea3
• Action: unknown@unknown