fix(code-reviews): sanitize summary and failure strings

[pandemicsyn]

Summary

• Fix KILOCODE-WEB-1G3Z: a NUL in a previous review summary makes PostgreSQL reject both summary persistence and the subsequent error-message write, leaving the review queued for repeated dispatch attempts.
• Reuse the existing PostgreSQL string repair helper at both write boundaries, preserving nulls, valid Unicode, and literal escape sequences.
• Add helper and real-database regression coverage for summary storage and successful failure terminalization.

Verification

No manual UI tests: this is a backend persistence fix verified through database-backed tests and static checks.

Automated Checks

• pnpm --filter web exec jest --runInBand src/lib/sanitize-jsonb.test.ts src/lib/code-reviews/db/code-reviews.test.ts — 2 suites, 50 tests passed.
• pnpm --filter web lint — passed.
• pnpm --filter web typecheck — passed.
• pnpm format on the four changed files and git diff --check — passed.

Visual Changes

N/A

Reviewer Notes

No schema migration. Reservation/status guards are unchanged. Independent static review completed: no code defects found. Its minor documentation note was corrected in a follow-up commit, and all targeted tests, lint, and typecheck passed again.

Sentry: https://kilo-code.sentry.io/issues/KILOCODE-WEB-1G3Z

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• apps/web/src/lib/sanitize-jsonb.ts
• apps/web/src/lib/sanitize-jsonb.test.ts
• apps/web/src/lib/code-reviews/db/code-reviews.ts
• apps/web/src/lib/code-reviews/db/code-reviews.test.ts

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_{Reviewed by grok-4.6 · Input: 115.9K · Output: 10.1K · Cached: 467.8K}

_{Review guidance: REVIEW.md from base branch main}