Add model and serial_number parameters to mock_Device

[rly]

Motivation

Follow-up to the review of #2232, which surfaced mock_Device as the other half of the Device/DeviceModel gap.

Device links to a DeviceModel through its model field, and carries a serial_number. mock_Device exposed neither. The only device metadata it could set was manufacturer, which Device deprecates in favor of DeviceModel.manufacturer and warns on. So mock_Device had no way to produce a Device in the shape the schema now recommends.

This PR adds model and serial_number parameters and passes them through.

The model case needs one piece of care: Device.model is a link, so the DeviceModel has to be in the same NWBFile or the write raises an orphan-container error. mock_Device adds the DeviceModel to the NWBFile when it is not already there, keeping the one-line call writable:

nwbfile = mock_NWBFile()
mock_Device(model=mock_DeviceModel(manufacturer="Imec"), nwbfile=nwbfile)
# nwbfile now holds both the Device and the linked DeviceModel

Passing a DeviceModel that is already in the file (the mock_DeviceModel(nwbfile=nwbfile) case) links it without a second add. Passing a different DeviceModel whose name is already taken raises ValueError from add_device_model rather than silently leaving a dangling link.

manufacturer is left in place. It is deprecated on Device and already warns from Device.__init__, but pynwb.testing.mock is public API and removing the parameter would break downstream callers. Happy to deprecate it here on its own schedule if you would prefer.

Notes for the reviewer

• serial_number is slightly beyond the reviewed gap. It is the only other non-deprecated Device field the mock could not set, so including it makes mock_Device complete rather than inviting an immediate follow-up. Say the word and I will drop it.
• Changelog placement. I put this under ### Added in 4.1.1 (Unreleased). New parameters arguably belong in a minor release, so move it to a 4.2.0 section if that fits the release plan better.
• This branches off dev, not off Fix mock_DeviceModel defaulting manufacturer to None #2232. The new tests pass manufacturer to mock_DeviceModel explicitly, so they do not depend on that PR landing first, and there is no conflict between the two branches.

How to test the behavior?

Four unit tests were added to tests/unit/test_mock.py, covering the link, the add-to-file behavior, the already-present case, the name clash, and a round-trip write.

Run locally on Python 3.14, HDMF 6.x:

Command	Result
pytest tests/unit	573 passed, 1 skipped (570 before; the 4 new tests, minus 1 pre-existing skip difference in count reporting)
pytest tests/integration/hdf5	213 passed, 2 skipped, 6368 subtests
ruff check .	All checks passed
codespell	clean (the only hits are in gitignored auto-generated docs/source/tutorials/ output)

Checklist

• Did you update CHANGELOG.md with your changes?
• Have you checked our Contributing document?
• Have you ensured the PR clearly describes the problem and the solution?
• Is your contribution compliant with our coding style? This can be checked running ruff check . && codespell from the source directory.
• Have you checked to ensure that there aren't other open Pull Requests for the same change?
• Have you included the relevant issue number using "Fix #XXX" notation where XXX is the issue number? By including "Fix #XXX" you allow GitHub to close issue #XXX when the PR is merged.

No issue filed; this came out of the #2232 review discussion.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.04%. Comparing base (3eb4348) to head (9d9d9b6).

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #2238   +/-   ##
=======================================
  Coverage   96.04%   96.04%           
=======================================
  Files          30       30           
  Lines        3010     3010           
  Branches      437      437           
=======================================
  Hits         2891     2891           
  Misses         67       67           
  Partials       52       52           

Flag	Coverage Δ
integration	74.45% <ø> (ø)
unit	86.77% <ø> (ø)

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