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/oscillators/trendflex/Trendflex.md

@@ -1,5 +1,7 @@
 # TRENDFLEX: Ehlers Trendflex Indicator
 
+> *The trend is your friend until it bends.*
+
 | Property         | Value                            |
 | ---------------- | -------------------------------- |
 | **Category**     | Oscillator                        |
@@ -16,8 +18,6 @@
 - Requires `period` bars of warmup before first valid output (IsHot = true).
 - Validated against TA-Lib, Skender, and Tulip reference implementations where available.
 
-> "The trend is your friend until it bends." — Ed Seykota, but Ehlers actually measures the bending.
-
 ## Introduction
 
 The Trendflex indicator combines a 2-pole Butterworth low-pass pre-filter (Super Smoother) with an O(1) cumulative slope measurement and exponential RMS normalization to produce a zero-centered oscillator that quantifies trend strength. Unlike conventional slope or momentum indicators that suffer from noise amplification or lag, Trendflex pre-smooths via the Super Smoother, computes the least-squares slope of the filtered signal over a lookback window in constant time, then normalizes by a running RMS estimate. The result: a bounded oscillator where values above zero indicate uptrend, below zero indicate downtrend, and magnitude reflects trend conviction.