Fix inverted and wrong factors in the units conversion table

[rundvd]

Pull request type

• Code changes (bugfix, features)

Checklist

• Tests for the changes have been added
• ruff format --check and ruff check pass on the changed files
• tests/unit passes locally except the Monte Carlo files, which I could not finish in my environment (nothing there uses rocketpy.units); the environment analysis and flight data importer integration tests also pass

Current behavior

Each UNITS_CONVERSION_DICT entry is the number of that unit in one base unit (1 m = 1e3 mm), but six entries do not follow that: deg, grad, mg and g are inverted, ft/s^2 holds the inverse of the correct factor, and atm is 1.01325e-5 instead of 1/101325. convert_units(np.pi, "rad", "deg") returns 0.0548. Because FlightDataImporter divides by these factors, a flight log recorded in ft/s^2 imports 10.8x too large and one recorded in degrees 3283x too large.

New behavior

The six factors are corrected. A parametrized test checks every non-temperature unit against its exact SI definition in both directions, and a new FlightDataImporter test covers ft/s^2 and degree columns.

Breaking change

• No (results change only for the six affected units)

Additional information

Found and fixed with AI assistance (Claude Opus 5.5); I reviewed the change and the tests fail before it and pass after.