Rename split-loop-with-lambda to slice-with-lambda

The refactoring is now published as Slice on sammancoaching.org:
https://sammancoaching.org/refactorings/slice.html

- git mv ideas/split-loop-with-lambda -> ideas/slice-with-lambda
- rename learning-hour file and update frontmatter name
- update paths in tools/rehearse scripts and report title
- update prose: 'Split Loop with Lambda' -> 'Slice with Lambda'
  in learning hour, exercise READMEs, storyboard, solution comments
- link the published Slice refactoring from the pattern draft

ideas/slice-with-lambda/exercise/csharp/solution/WeatherStationSolution.cs

@@ -0,0 +1,72 @@
+// Example 2 solution — Weather Station domain demo of Slice with Lambda (C#), after
+//
+// Lambda extracted (step 1), slid to the top (step 2), method extracted
+// below the guard (step 3). The constructor now takes the lambda directly,
+// so tests construct with new SprinklerController(() => 200).
+//
+// Condensed mechanics: https://sammancoaching.org/refactorings/slice.html
+// (where that page says mock, we use a lambda instead).
+
+using System;
+
+public enum SunExposure
+{
+    Shady,
+    Sunny
+}
+
+public enum WateringDuration
+{
+    None,
+    Medium,
+    Short
+}
+
+public class LightSensor
+{
+    private readonly Random _rng = new Random();    // stand-in for hardware noise
+
+    public byte Read()
+    {
+        return (byte)_rng.Next(256);
+    }
+}
+
+public class SprinklerController
+{
+    private readonly Func<byte> _readLight;         // the sensor, as a lambda
+    private bool _wateredToday;                     // event-style client state
+
+    public SprinklerController(Func<byte> readLight)
+    {
+        _readLight = readLight;
+    }
+
+    public WateringDuration ScheduleWatering()
+    {
+        Func<byte> readLight = () => _readLight();  // lambda definition at the top
+        return ScheduleWateringTail(readLight);     // pass the lambda on
+    }
+
+    private WateringDuration ScheduleWateringTail(Func<byte> readLight)
+    {
+        if (_wateredToday)                          // guard: client state, stays
+        {
+            return WateringDuration.None;
+        }
+
+        _wateredToday = true;                       // set only after watering
+        byte reading = readLight();                 // middle: the stubbed lambda
+        SunExposure exposure = ToSunExposure(reading);
+        if (exposure == SunExposure.Sunny)          // tail: complex behaviour below
+        {                                           // the extraction point
+            return WateringDuration.Medium;
+        }
+        return WateringDuration.Short;
+    }
+
+    private static SunExposure ToSunExposure(byte reading)
+    {
+        return reading > 128 ? SunExposure.Sunny : SunExposure.Shady;
+    }
+}