Merge branch 'dev'

lib/filters/usf/Usf.md

@@ -14,9 +14,7 @@
 | **Signature**    | [usf_signature](usf_signature.md) |
 
 - The Ultimate Smoother Filter (USF) is a zero-lag smoothing filter introduced by John Ehlers in the April 2024 issue of *Technical Analysis of Stock...
-- Parameterized by `period`.
-- Output range: Tracks input.
-- Requires `period` bars of warmup before first valid output (IsHot = true).
+- **Similar:** [SSF2](../ssf2/Ssf2.md), [Kalman](../kalman/Kalman.md) | **Complementary:** ATR for volatility | **Trading note:** Universal Smoothing Filter; combines multiple filter approaches adaptively.
 - Validated against TA-Lib, Skender, and Tulip reference implementations where available.
 
 The Ultimate Smoother Filter (USF) is a zero-lag smoothing filter introduced by John Ehlers in the April 2024 issue of *Technical Analysis of Stocks & Commodities*. It builds upon the Super Smoother Filter (SSF) by using a high-pass filter to remove high-frequency noise, leaving a smooth low-frequency component with minimal lag.
@@ -119,4 +117,4 @@ Console.WriteLine($"Current USF: {usf.Last.Value}");
 
 // Use in a TSeries chain
 var source = new TSeries();
-var usfSeries = new Usf(source, 20);
+var usfSeries = new Usf(source, 20);