Wire durable auto-review runtime dedupe

[shiny-code-bot]

Summary

• Wire the durable auto-review store into background runtime scheduling so equivalent completed background reviews are reused instead of spending another review request.
• Add target-filtered duplicate lookup/supersession helpers so unowned in-flight records do not shadow reusable completed runs, and clean terminal supersession does not cross branch/head boundaries.
• Persist duplicate candidates as skipped records with duplicate metadata while preserving the existing app-server/TUI background status contract.

Refs #130

Validation

• cargo test -p codex-auto-review
• cargo test -p codex-core save_skipped_duplicate_records_duplicate_metadata
• cargo test -p codex-core automatic_background_review_reuses_completed_durable_duplicate --test all -- --nocapture
• cargo test -p codex-core automatic_background_review_suppresses_unchanged_dirty_diff --test all -- --nocapture
• cargo fmt --manifest-path codex-rs/Cargo.toml --all --check (passes with existing stable-rustfmt warnings)
• git diff --check
• Read-only GPT-5.5 patch review after repairs: no issues found.
• Built-in mini auto-review failed before findings on this patch (fb268d17-bafa-415c-b232-208b85991b2d), so it produced no actionable findings.