test: make local test helpers importable in subprocesses

[Birfy]

Reproduced problem

On unchanged main, tests/ was a namespace package. This host also has unrelated regular tests and scripts packages in Anaconda's Python 3.9 site-packages. The detached worker resolves tests.test_evolvespec:stub_reflect in a fresh process, where the installed tests package shadows the repository namespace.

The existing test_start_status_show_apply_flow then ended at round 0 with:

SpecError: reflect: 'tests.test_evolvespec:stub_reflect': cannot import
'tests.test_evolvespec' (No module named 'tests.test_evolvespec').

The repro used the local deterministic stub spec with OPENAI_API_KEY and OPENAI_BASE_URL unset; it made no model/API calls.

Fix

• Make tests and scripts explicit packages so their local modules win over unrelated installed packages.
• Add tests/ to pytest's configured import path to preserve existing top-level test helper imports.
• Add a regression test that simulates conflicting installed tests and scripts packages.

This is separate from PR #201 and changes no runtime package behavior.

Verification

• Reproduced on unchanged main tree cf19d2be37f2fd295efcb32e57a5d590b4b13961 (main 368f9a85d6da7f65d67ff82138c6348da8e78c8b).
• After the fix: full pytest --collect-only -q succeeded locally; focused MCP, EvolveSpec, package-resolution and packaging tests: 56 passed, 2 skipped across the recorded runs, with provider credentials unset.
• Exact-head CI passed at 7ab7cca35b64a04e259be823f3b1228831dafa35: tests, wheel build and wheel smoke on Python 3.9, 3.10, 3.11 and 3.12; strict docs build passed. Docs deploy skipped for the PR as expected.
• The initial PR head exposed collection errors in legacy helper imports. The pytest path config and explicit scripts package address those; the corrected exact head is green.

Independent review is clean; the PR is Ready for review.

[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 2026-10-09T23:48:50.426829Z	7ab7cca	Draft marked ready

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