feat(dynamics): add PlusDI, MinusDI, PlusDM, MinusDM indicators

Complete thin Dx-composition wrapper indicators with full test coverage:

- PlusDi/MinusDi: Directional Indicator wrappers (DiPlus/DiMinus from Dx)
- PlusDm/MinusDm: Directional Movement wrappers (DmPlus/DmMinus from Dx)
- Individual validation tests per indicator directory (TALib, Skender, bounds)
- Combined unit tests (DiDm.Tests.cs) and validation tests (DiDm.Validation.Tests.cs)
- Quantower wrappers + tests for all 4 indicators
- PineScript v6 implementations with compensated RMA
- Normalized .md documentation for all indicators and categories
- 182 tests passing, 0 failures

lib/core/medprice/Medprice.md

@@ -1,5 +1,7 @@
 # MEDPRICE: Median Price
 
+> *The midpoint of high and low captures the bar's central tendency, ignoring where it opened or closed.*
+
 | Property         | Value                            |
 | ---------------- | -------------------------------- |
 | **Category**     | Core                        |
@@ -62,20 +64,6 @@ $O(1)$ per bar. One addition, one multiply. No memory allocation. Always hot aft
 | AVGPRICE | O, H, L, C | Equal | Fully balanced |
 | WCLPRICE | H, L, C | C double-weighted | Close-biased |
 
-### Pseudo-code
-
-```
-function MEDPRICE(bar):
-    h, l ← bar.High, bar.Low
-
-    // Substitute last-valid for non-finite inputs
-    if !finite(h): h ← lastValidHigh
-    if !finite(l): l ← lastValidLow
-
-    result ← (h + l) × 0.5
-    return result
-```
-
 ### Output Interpretation
 
 | Context | Meaning |