🤖 This PR was created by Repo Assist in response to issue #563.

Summary

This PR adds a new Deedle.MicrosoftML package that bridges Deedle's Frame<'R, string> / Series<'K, 'V> types with ML.NET's IDataView pipeline infrastructure.

What's included

src/Deedle.MicrosoftML/

tests/Deedle.MicrosoftML.Tests/

17 tests covering:

• Schema inference for numeric, string, bool columns
• Cursor iteration + correct values
• Round-trip Frame → IDataView → Frame
• Missing value propagation (NaN / empty string)
• ML.NET NormalizeMinMax transform integration
• fitEstimator / applyTransformer separation of concerns
• fitTransformOn (train on one frame, transform another)
• Extension methods

Other changes

• paket.dependencies – adds nuget Microsoft.ML (resolved to 5.0.0)
• Deedle.sln – adds both new projects

Usage (F#)

open Deedle
open Deedle.MicrosoftML
open Microsoft.ML

let mlc = MLContext(seed = 1)

// Convert a Deedle frame to IDataView for ML.NET
let dv : IDataView = Frame.toDataView myFrame

// Fit and apply a normaliser, get result back as a Frame
let normalised : Frame(int, string) =
    Pipeline.fitTransform (mlc.Transforms.NormalizeMinMax("Price_norm", "Price")) myFrame

// Convert any ML.NET IDataView output back to Deedle
let result : Frame(int, string) = Frame.ofDataView someDataView

Usage (C#)

using Deedle;
using Deedle.MicrosoftML;

var dv      = frame.ToDataView();
var result  = frame.FitTransform(mlc.Transforms.NormalizeMinMax("X_norm", "X"));
```

## Column type mapping

| Deedle type | ML.NET type |
|---|---|
| `float` | `Double` |
| `float32` | `Single` |
| `int` | `Int32` |
| `int64` | `Int64` |
| `bool` | `Boolean` |
| `string` | `Text` (`ReadOnlyMemory(char)`) |
| Missing float | `NaN` |
| Missing string | `""` |

## Test status

```
✅ 17 / 17 tests pass (Deedle.MicrosoftML.Tests)
✅ 685 / 685 tests pass (Deedle.Tests – no regressions)

Closes #563
Epic: #676

Generated by Repo Assist for issue #563 · ◷

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