ci: split build into lint and test workflows with a Windows matrix

[sherjy]

Summary

Split the single build.yml job into two workflows so lint runs once on Linux while tests gain an OS matrix that includes Windows.

• lint.yml — ubuntu-latest, Python 3.13; runs make check (lock-file check, pre-commit, mypy, deptry) exactly once.
• test.yml — matrix {ubuntu-latest, windows-latest} × {3.11, 3.13}, fail-fast: false; runs pytest with coverage directly (not via make, which isn't guaranteed on windows-latest).
• Removes build.yml. pr-title.yml, publish-memu-cli.yml, and release-please.yml are untouched.
• Both workflows keep the existing same-repo dedupe if: guard, so branch pushes and fork PRs behave exactly as before.

Closes #505.

Why

Per #505, adding Windows to the combined job would rerun lint/pre-commit on every OS×Python cell and pull pre-commit onto Windows, where its hooks have CRLF pitfalls (cf. #482). Keeping lint single-run on ubuntu and giving only pytest the OS matrix avoids that and lets platform-specific test failures surface.

Surfaced and fixed a real Windows-only failure

Enabling windows-latest immediately caught one — exactly the point of #505. tests/test_host_templates.py::test_fetch_rejects_bad_responses_without_caching has an "oversize" case that builds a 65,537-byte body, so pytest derived a node id longer than Windows' 32,767-character limit for the PYTEST_CURRENT_TEST environment variable. Setup and teardown then raised ValueError: the environment variable is longer than 32767 characters on Windows only (Linux has no such cap).

Fixed by giving each parametrization a short, explicit pytest.param(..., id=...). The request bodies and assertions are unchanged, so the size guard is still exercised.

Verification

Locally on Windows (Python 3.13):

• pytest → 222 passed, 0 errors (previously 221 passed + 2 errors before the id fix).
• make check: pre-commit, mypy (129 source files), deptry, and uv lock --locked all clean.

CI on this PR additionally covers ubuntu × {3.11, 3.13} and windows × {3.11, 3.13}.

Notes for maintainers

• I kept the existing {3.11, 3.13} Python pair in test.yml (build.yml already tested both) and added the OS dimension. Happy to reduce to 3.13-only if you prefer the exact shape proposed in [IMPROVEMENT] Split CI: separate lint from test, paving the way for a Windows test matrix #505.
• Branch protection's required status checks will need updating from build to lint and test.

[MrXnneHang]

感谢你的 PR~

关于 windows CI 的引入我之前提过一次，但当时没有结果。

memU 确实需要引入跨平台的 ci，但不是现在。

因为跨平台测试目前不应该被所有代码改动触发，对于 memU 的主体它是跨平台安全的。

需要被测试的主要是各个 host 的跨平台 macos cron 和 windows scheduler 的部分。而这部分代码最近会频繁新增和删减。现在引入跨平台单测 ci 会需要频繁修改 ci 文件。

为了更快的开发，当前更倾向手动测试，等到跨平台支持稳定后，再新增按需触发的 CI workflow。

一个始终触发的 windows / macOS workflow 会拖慢 CI 的进行速度，当前并不希望如此。