Reviewers: inline line-anchored comments + finding dedup / carry-forward (gersmann pattern)

Problem

All executors (codex, bedrock-generic, claude) post a single sticky blob comment. Two consequences:

1. No line anchoring — findings reference file:line in prose but aren't attached to the diff, so reviewers can't see them in context.
2. No dedup / repeat-suppression — the model can emit the same finding twice in one run (observed on IaC #7889: the identical line-50 finding posted twice), and across re-runs there's no memory of what was already raised or resolved.

Reference implementation

gersmann/codex-review-action (OpenAI Responses API, same family we run on mantle) does this well:

• inline comments anchored to exact diff lines; skip a finding if its target line isn't in the diff
• structured JSON output (findings, carried_forward, overall_*) instead of freeform markdown
• prior unresolved findings are fed back to the model so it carries forward still-relevant ones and avoids reposting
• PR-level summary refreshed each run (old summary deleted); summary-only when there are no findings
• severity tags 🔴 [P0] / [P1], 🟡 [P2], ⚪ [P3]; "prefer returning none"

Ask

Move the reviewers from "one sticky blob" toward: structured findings → inline anchored review comments + a refreshed summary, with dedup/carry-forward across runs. Likely a shared helper so all executor paths benefit. This is a real change + new release.

Refs: IaC #7889, #${ISSUE1##*/} (tight default prompt — complementary).

Start by tracing the codex, bedrock-generic, and claude executor paths, then compare their review flow with the linked gersmann/codex-review-action reference. Done means shared structured findings produce diff-anchored comments, suppress duplicates, carry unresolved findings across runs, and refresh a PR-level summary for all executor paths.