Add a units option to get predictions in feet

[bkeepers]

getExtremesPrediction({
  // …
  units: 'feet'
})

getTimelinePrediction({
  // …
  units: 'feet'
})

getWaterLevelAt({
  // …
  units: 'feet'
})

The level value is returned in feet instead of meters.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (68da259) to head (76095a0).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files           11        11           
  Lines          505       522   +17     
  Branches        54        58    +4     
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+ Hits           505       522   +17     

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[Copilot]

Pull request overview

This PR adds a units option to three main functions (getExtremesPrediction, getTimelinePrediction, and getWaterLevelAtTime) allowing users to request water level predictions in feet instead of the default meters.

• Adds a Units type and units parameter with 'meters' (default) and 'feet' options
• Implements unit conversion using a toPreferredUnits helper function with a conversion factor of 3.2808399 feet per meter
• Updates return types to include the units field in prediction results

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/neaps/src/index.ts	Core implementation of the units option, including type definitions, conversion logic, and integration into all three prediction functions
packages/neaps/test/index.test.ts	Test coverage for the new units functionality across all prediction functions, including error handling for unsupported units
examples/units.ts	Example demonstrating how to use the units option to compare meters and feet predictions
README.md	Documentation updates showing the units parameter in all three function examples with output samples

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