refactor: consolidate geometry assertions and improve test robustness…

[kashi-verma]

… in TestDPM

Refactor geometry assertions into a private helper method _assert_geometry.

Fix off-by-one error in test_get_apparent_wind loop.

Update floating-point assertions to use pytest.approx for clearer intent.

Standardize string formatting to f-strings across the test suite.

Related Issue / Discussion:

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Fixes Issue #XX

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Changes:

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• Modified class / file / …

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