test: isolate utility queue transactions in CI

[DeusExTaco]

Summary

• Give utility queue integration tests a per-test file-backed SQLite database so dispatch writers and cancellation readers use independent connections, matching production.
• Commit test setup before dispatch rather than relying on uncommitted data leaking across sessions.
• Add a deterministic regression proving that closing a status reader cannot roll back a pending writer update.

Why

The exact-commit develop gate exposed timing-dependent lost updates in three queue tests after #154. The old shared in-memory connection allowed one session to roll back another session's writes. The new regression fails under that fixture and passes with independent connections.

Validation

• All 94 queue and cancellation tests pass, with all original result/history assertions retained.
• Ruff lint and formatting pass.
• A fresh make ci-full is running for this follow-up; the application code already passed the complete local gate and PR fix: harden import recovery and utility cancellation #154 checks.

Scope

Test-only change. No runtime behavior, safety checks, coverage thresholds, or production files changed. Edge publication remains held until the merged commit passes all release gates.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-19T03:03:25.907257Z	b607b0c	PR opened

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[DeusExTaco]

The fresh make ci-full run passed completely: 12,023 application tests at 91.16% coverage, 25 accessibility tests, 575 browser tests in each browser, and all 7 production-image smoke tests. The GitHub Python 3.12, 3.13, and 3.14 jobs also passed with the isolated fixture. No runtime changes or weakened assertions were needed.

[DeusExTaco]

Merged and included in the successful edge publication: https://github.com/pullboxapp/pullbox/actions/runs/35419313435 . The final develop commit d965657 passed the Python 3.12/3.13/3.14 matrix and all required release gates. Version 1.3.1-dev is verified on both platforms and both registries; production latest was not changed.