refactor(runner): изменена модель с haiku на sonnet

- Зачем:
  - Sonnet обеспечивает лучшее соотношение цена/качество для runner subagent.
- Что:
  - AGENTS.md: обновлено описание runner subagent (model: haiku → sonnet).
  - SKILL.md: обновлены все ссылки на модель runner в Agent tool и документации.
  - docs/DESIGN.md: обновлено описание модели в §12.5 и §12.6.
- Проверка:
  - git diff HEAD~1 -- AGENTS.md SKILL.md docs/DESIGN.md.

docs/DESIGN.md

@@ -1451,7 +1451,7 @@ Before this split, the entire skill ran in the main Claude thread. Each round's
 
 Claude Code's Agent tool dispatches a fresh subagent with its own isolated context. When the subagent returns, its context is discarded; only its final text message crosses to main. By making the runner subagent own every codex-exec artifact and return only a ~1KB JSON summary file plus the small review file path, the main thread no longer pays the residue tax.
 
-The runner uses a two-channel protocol: the authoritative structured result is written to `/tmp/codex-runner-result-${REVIEW_ID}.json`, and the runner's final message is a single `RUNNER_RESULT_AT: <path>` line. Main extracts the path with a tolerant regex (markdown fences and minor wrapping do not break parsing) and reads the JSON file directly. This avoids the brittle "raw JSON in message" contract that Haiku's conversational output style would otherwise stress.
+The runner uses a two-channel protocol: the authoritative structured result is written to `/tmp/codex-runner-result-${REVIEW_ID}.json`, and the runner's final message is a single `RUNNER_RESULT_AT: <path>` line. Main extracts the path with a tolerant regex (markdown fences and minor wrapping do not break parsing) and reads the JSON file directly. This avoids the brittle "raw JSON in message" contract that Sonnet's conversational output style would otherwise stress.
 
 **Runner spec is passed by path, not inlined.** Main resolves `RUNNER_SPEC_PATH` (3-tier filesystem lookup in SKILL.md Step 4) and passes the absolute path to the subagent — the subagent Reads runner.md itself. Main never Reads runner.md. Rationale: inlining the full spec (~12K) into every Agent-tool prompt would re-add ~12K × rounds (up to 5) to main's context per review — 60K of avoidable overhead. Bootstrap instruction in the Agent prompt is ~400 bytes; the spec lives only in the disposable subagent context.
 
@@ -1469,9 +1469,9 @@ Resume-to-fresh-exec fallback requires archiving the failed-resume stdout/stderr
 
 ### §12.5 Model choice
 
-The runner is a pure pipeline executor: parse inputs, call Bash, validate output, retry once, archive on resume failure, write result JSON. No code understanding, no severity judgment, no review interpretation. Haiku 4.5 is sufficient and ~15× cheaper per token than Opus. The main thread (Opus) keeps all judgment work (applying fixes, deciding round progression, user interaction).
+The runner is a pure pipeline executor: parse inputs, call Bash, validate output, retry once, archive on resume failure, write result JSON. No code understanding, no severity judgment, no review interpretation. Sonnet is sufficient and cheaper per token than Opus. The main thread (Opus) keeps all judgment work (applying fixes, deciding round progression, user interaction).
 
-To avoid confusion, the runner's input schema uses `CODEX_MODEL` (the model codex CLI launches) — distinct from the runner's OWN model, which is passed via the Agent tool's `model: "haiku"` parameter. The names are intentionally non-overlapping.
+To avoid confusion, the runner's input schema uses `CODEX_MODEL` (the model codex CLI launches) — distinct from the runner's OWN model, which is passed via the Agent tool's `model: "sonnet"` parameter. The names are intentionally non-overlapping.
 
 ### §12.6 Invariants preserved