docs: remove C# Implementation Considerations sections, clean up temp scripts, reorganize test files

- Remove 'C# Implementation Considerations' sections from 34 indicator .md files
- Delete 29 temp PowerShell scripts (_fix_mojibake.ps1, _hex_scan.ps1, etc.)
- Move test files into tests/ subdirectories for consistent project structure
- Add trader-focused bullet points to indicator documentation

lib/errors/mae/tests/Mae.Validation.Tests.cs

@@ -0,0 +1,100 @@
+using MathNet.Numerics;
+using QuanTAlib.Tests;
+
+namespace QuanTAlib.Validation;
+
+public sealed class MaeValidationTests : IDisposable
+{
+    private readonly ValidationTestData _data = new();
+
+    public void Dispose() => _data.Dispose();
+
+    [Fact]
+    public void Mae_Matches_MathNet()
+    {
+        int[] periods = { 5, 10, 20, 50, 100 };
+
+        var quotes = _data.SkenderQuotes.ToList();
+        double[] actual = quotes.Select(q => (double)q.Close).ToArray();
+        double[] predicted = quotes.Select(q => (double)q.Open).ToArray();
+
+        foreach (int period in periods)
+        {
+            var mae = new Mae(period);
+
+            for (int i = 0; i < actual.Length; i++)
+            {
+                var val = mae.Update(
+                    new TValue(quotes[i].Date, actual[i]),
+                    new TValue(quotes[i].Date, predicted[i]));
+
+                // Validate last 100 bars
+                if (i >= actual.Length - 100 && i >= period - 1)
+                {
+                    var windowActual = actual[(i - period + 1)..(i + 1)];
+                    var windowPredicted = predicted[(i - period + 1)..(i + 1)];
+
+                    double expected = Distance.MAE(windowActual, windowPredicted);
+
+                    Assert.Equal(expected, val.Value, 1e-9);
+                }
+            }
+        }
+    }
+
+    [Fact]
+    public void Mae_Batch_Matches_MathNet()
+    {
+        int[] periods = { 5, 10, 20, 50, 100 };
+
+        var quotes = _data.SkenderQuotes.ToList();
+        double[] actual = quotes.Select(q => (double)q.Close).ToArray();
+        double[] predicted = quotes.Select(q => (double)q.Open).ToArray();
+
+        foreach (int period in periods)
+        {
+            double[] output = new double[actual.Length];
+            Mae.Batch(actual, predicted, output, period);
+
+            // Validate last 100 bars
+            for (int i = actual.Length - 100; i < actual.Length; i++)
+            {
+                if (i >= period - 1)
+                {
+                    var windowActual = actual[(i - period + 1)..(i + 1)];
+                    var windowPredicted = predicted[(i - period + 1)..(i + 1)];
+
+                    double expected = Distance.MAE(windowActual, windowPredicted);
+
+                    Assert.Equal(expected, output[i], 1e-9);
+                }
+            }
+        }
+    }
+
+    [Fact]
+    public void Mae_Correction_Recomputes()
+    {
+        var ind = new Mae(20);
+
+        // Build state well past warmup
+        for (int i = 0; i < 50; i++)
+        {
+            ind.Update(100.0 + (i * 0.5), 98.0 + (i * 0.5));
+        }
+
+        // Anchor bar
+        const double anchorActual = 125.0;
+        const double anchorPredicted = 123.0;
+        ind.Update(anchorActual, anchorPredicted, isNew: true);
+        double anchorResult = ind.Last.Value;
+
+        // Correction with dramatically different values — recompute must yield different result
+        ind.Update(anchorActual * 10, anchorPredicted * 10, isNew: false);
+        Assert.NotEqual(anchorResult, ind.Last.Value);
+
+        // Correction back to original — must exactly restore original result
+        ind.Update(anchorActual, anchorPredicted, isNew: false);
+        Assert.Equal(anchorResult, ind.Last.Value, 1e-9);
+    }
+}