Need shareable MOUSE and Water Hammer fixtures to support those formats in Network

[jpalm3r]

Network now has one constructor per modelling product, and each one exists only where a committed test fixture backs it:

Constructor	Extensions	Fixture
Network.from_mike	.res1d, .res11	tests/testdata/network.res1d, network_cali.res11
Network.from_epanet	.res	tests/testdata/epanet.res

Two of the formats mikeio1d can open are refused purely because we have no file to test them with:

• MOUSE — .prf, .crf, .xrf
• Water Hammer — .whr

Neither has a result file in this repo or in mikeio1d's testdata, so there is no way to check whether the existing loader produces a correct network for them. Both currently raise:

NotImplementedError: Cannot read '.prf' files. MOUSE results are not supported
yet: modelskill has no test fixture for this format, so support cannot be
verified. Please open an issue if you need it.

What would help: a small, redistributable result file for either format — ideally from a public or synthetic model rather than a client project. Once one lands in tests/testdata, adding the constructor is a docstring plus one delegating call to Network._from_mikeio1d, and the extension moves from _UNSUPPORTED_EXTENSIONS to its own set in src/modelskill/network.py.

One caveat worth recording for whoever picks this up: for MOUSE extensions mikeio1d calls ResultData.Load() and rebuilds res1d.network on the first data read (result_reader.py:141-146), with a comment noting that existing network references are invalidated. Network._load_res1d_network captures ResultReach objects and then triggers that read, so MOUSE support may need the load forced up front. That cannot be confirmed without a fixture.

Not fixture problems

Two other formats are refused for a different reason, and no fixture will change that:

• SWMM (.out) — mikeio1d cannot resolve reach start/end nodes. ResultReachCreator._get_start_node indexes result_data.Nodes[reach.StartNodeIndex] and raises ArgumentOutOfRangeException; mikeio1d's own test_swmm_network.py never touches reach connectivity.
• .resx — ResultReach.start_node/end_node return None by design.

Both are upstream gaps rather than modelskill bugs. tests/testdata/swmm.out and epanet.resx are committed and asserted against, so if a future mikeio1d starts exposing connectivity for either, those tests fail and tell us a constructor is now possible.

An EPANET file from a confidential project was also used during development to sanity-check from_epanet at scale (~8000 reaches); it cannot be committed, hence the smaller public fixture.

[jpalm3r]

#687 confirms this is a fixture problem, not a code problem: no MOUSE or Water Hammer result file exists in this repo or in mikeio1d's testdata to test against. Still needs a contributed fixture.