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/statistics/zscore/Zscore.md

@@ -1,5 +1,7 @@
 # ZSCORE: Z-Score (Population Standard Score, also known as STANDARDIZE)
 
+> *How far from normal is this?*
+
 | Property         | Value                            |
 | ---------------- | -------------------------------- |
 | **Category**     | Statistic                        |
@@ -16,8 +18,6 @@
 - Requires `period` bars of warmup before first valid output (IsHot = true).
 - Validated against manual computation, PineScript parity, and statistical invariants.
 
-> "How far from normal is this?" — Every risk manager, every day.
-
 ## Introduction
 
 The Z-Score measures how many population standard deviations a value lies from the rolling mean over a lookback window. ZSCORE is the canonical implementation for z-score standardization in QuanTAlib (the former Standardize indicator, which used sample standard deviation with N-1, has been consolidated into this indicator). ZSCORE uses population standard deviation, matching the PineScript `ta.zscore` convention. Output is unbounded, typically ranging from -3 to +3 for normally distributed data. A z-score of 0 means the value equals the window mean; ±2 flags statistical outliers at the 95% level.