feat: Family 07 Volume - 6 new volume-flow indicators (#45)

* feat(kvo): add Klinger Volume Oscillator

Stephen J. Klinger's trend-aware volume-force MACD. Each bar produces a 'volume force' (vf) signed by the local trend (+1 / -1 / carry) and scaled by the ratio of the current accumulation horizon to its previous trend. KVO = EMA(vf, fast) - EMA(vf, slow), classic (34, 55).

Rust core (Kvo) with 7 unit tests (rejects zero / fast>=slow, accessors, constant series collapses to 0, warmup lands at slow+1, batch == streaming, reset clears state), plus Python (PyKvo + KVO export), Node (KvoNode), and WASM (WasmKvo) bindings. Fuzz target adds Kvo to the candle-input sweep, bench adds the candle-input KVO benchmark, README counter 71 -> 72 + family table row, CHANGELOG [Unreleased].

* feat(volume-oscillator): add Volume Oscillator (VO)

Percent difference between a fast and a slow SMA of the bar volume: 100 * (SMA(vol, fast) - SMA(vol, slow)) / SMA(vol, slow). Default (14, 28). The line stays near zero in stable conditions; positive readings show rising short-term participation, negative readings show waning interest.

Rust core (VolumeOscillator) with 8 unit tests (period validation, accessors, constant volume == 0, zero-volume window defensive branch, two reference values verified algebraically, batch == streaming, reset), plus Python (PyVolumeOscillator + VolumeOscillator export), Node (VolumeOscillatorNode), and WASM (WasmVolumeOscillator) bindings. Fuzz target adds VolumeOscillator to the candle-input sweep, bench adds the volume_oscillator benchmark, README counter 72 -> 73 + family table row, CHANGELOG [Unreleased].

* feat(nvi-pvi): add Negative & Positive Volume Index

Paul Dysart's cumulative volume-flow indices, popularised by Norman Fosback in 'Stock Market Logic'. Both run from a 1000.0 baseline and only update on a specific direction of volume change:

- NVI updates on volume-contraction bars (volume_t < volume_{t-1}), absorbing the percent close change. Tracks the 'smart money' leg per Fosback.
- PVI updates on volume-expansion bars (volume_t > volume_{t-1}). Tracks the 'crowd' leg.

Both expose with_baseline(f64) for custom starting indexes. The NVI/PVI pair is listed as a single line in indicator-ideas/families/07-volume.md and shares the same lifecycle/test/binding surface, so they ship as one commit.

Rust core (Nvi, Pvi) with 9 unit tests each (accessors, baseline seed, volume direction branches, zero-prev-close guard, custom baseline, batch == streaming, reset), plus Python (PyNvi/PyPvi + NVI/PVI exports), Node (NviNode/PviNode), and WASM (WasmNvi/WasmPvi) bindings. Fuzz target adds Nvi+Pvi to the candle-input sweep, bench adds nvi+pvi entries, README counter 73 -> 75 + family table row, CHANGELOG [Unreleased].

* feat(family-07): add Williams A/D, Anchored VWAP, Demand Index, TSV, VZO, Market Facilitation Index

Finishes the volume-flow family with the remaining (new) entries from
indicator-ideas/families/07-volume.md.

Indicators added:

- Williams A/D (`WilliamsAD`): Larry Williams' volume-less cumulative
  accumulation/distribution line. Anchors each bar's contribution to
  the previous close via true-high/true-low (gap-aware).
- Anchored VWAP (`AnchoredVwap`): cumulative VWAP whose accumulation
  starts at a user-chosen anchor bar. Exposes `set_anchor()` (queued
  to the next `update`) for click-to-anchor workflows. Reset clears
  both state and pending-anchor flag.
- Demand Index (`DemandIndex`): James Sibbet's smoothed buying-vs-
  selling pressure, in the streaming-friendly textbook form
  `EMA(volume * close-return * (1 + range/close), period)`.
- Time Segmented Volume (`Tsv`): Don Worden's rolling window-sum of
  `(close_t - close_{t-1}) * volume_t`. Default `period = 18`.
- Volume Zone Oscillator (`Vzo`): Walid Khalil's normalised volume-flow
  oscillator bounded in `[-100, +100]`, defined as
  `100 * EMA(signed_volume) / EMA(volume)`.
- Market Facilitation Index (`MarketFacilitationIndex`): Bill Williams'
  per-bar `(high - low) / volume`. Returns `None` on zero-volume bars.

All six indicators ship with unit tests (`rejects_zero_period` where
applicable, `accessors_and_metadata`, constant-series behaviour,
batch == streaming equivalence, reset semantics, and reference-value
or saturation-extreme tests), Python / Node / WASM bindings, fuzz
coverage in `indicator_update_candle`, a `bench_candle_input` line per
indicator, README + CHANGELOG entries, and Python reference-value
tests in `test_new_indicators.py`.

The README indicator counter advances 75 -> 81.

* test(family-07): cover defensive cold paths + Default impls

- ad_oscillator: exercise `value()` after first emission.
- kvo: cover the `cm == 0.0` zero-OHLC defensive branch.
- nvi / pvi: exercise the Default impls.

crates/wickra-core/src/indicators/mod.rs

@@ -6,11 +6,13 @@
 
 mod acceleration_bands;
 mod accelerator_oscillator;
+mod ad_oscillator;
 mod adl;
 mod adx;
 mod adxr;
 mod alligator;
 mod alma;
+mod anchored_vwap;
 mod apo;
 mod aroon;
 mod aroon_oscillator;
@@ -34,6 +36,7 @@ mod cmo;
 mod connors_rsi;
 mod coppock;
 mod dema;
+mod demand_index;
 mod donchian;
 mod double_bollinger;
 mod dpo;
@@ -53,6 +56,7 @@ mod jma;
 mod kama;
 mod keltner;
 mod kst;
+mod kvo;
 mod laguerre_rsi;
 mod linreg;
 mod linreg_angle;
@@ -60,12 +64,14 @@ mod linreg_channel;
 mod linreg_slope;
 mod ma_envelope;
 mod macd;
+mod market_facilitation_index;
 mod mass_index;
 mod mcginley_dynamic;
 mod median_price;
 mod mfi;
 mod mom;
 mod natr;
+mod nvi;
 mod obv;
 mod parkinson;
 mod percent_b;
@@ -73,6 +79,7 @@ mod pgo;
 mod pmo;
 mod ppo;
 mod psar;
+mod pvi;
 mod roc;
 mod rogers_satchell;
 mod rsi;
@@ -96,17 +103,20 @@ mod trima;
 mod trix;
 mod true_range;
 mod tsi;
+mod tsv;
 mod ttm_squeeze;
 mod typical_price;
 mod ulcer_index;
 mod ultimate_oscillator;
 mod vertical_horizontal_filter;
 mod vidya;
+mod volume_oscillator;
 mod vortex;
 mod vpt;
 mod vwap;
 mod vwap_stddev_bands;
 mod vwma;
+mod vzo;
 mod wave_trend;
 mod weighted_close;
 mod williams_r;
@@ -118,11 +128,13 @@ mod zlema;
 
 pub use acceleration_bands::{AccelerationBands, AccelerationBandsOutput};
 pub use accelerator_oscillator::AcceleratorOscillator;
+pub use ad_oscillator::AdOscillator;
 pub use adl::Adl;
 pub use adx::{Adx, AdxOutput};
 pub use adxr::Adxr;
 pub use alligator::{Alligator, AlligatorOutput};
 pub use alma::Alma;
+pub use anchored_vwap::AnchoredVwap;
 pub use apo::Apo;
 pub use aroon::{Aroon, AroonOutput};
 pub use aroon_oscillator::AroonOscillator;
@@ -146,6 +158,7 @@ pub use cmo::Cmo;
 pub use connors_rsi::ConnorsRsi;
 pub use coppock::Coppock;
 pub use dema::Dema;
+pub use demand_index::DemandIndex;
 pub use donchian::{Donchian, DonchianOutput};
 pub use double_bollinger::{DoubleBollinger, DoubleBollingerOutput};
 pub use dpo::Dpo;
@@ -165,6 +178,7 @@ pub use jma::Jma;
 pub use kama::Kama;
 pub use keltner::{Keltner, KeltnerOutput};
 pub use kst::{Kst, KstOutput};
+pub use kvo::Kvo;
 pub use laguerre_rsi::LaguerreRsi;
 pub use linreg::LinearRegression;
 pub use linreg_angle::LinRegAngle;
@@ -172,12 +186,14 @@ pub use linreg_channel::{LinRegChannel, LinRegChannelOutput};
 pub use linreg_slope::LinRegSlope;
 pub use ma_envelope::{MaEnvelope, MaEnvelopeOutput};
 pub use macd::{MacdIndicator, MacdOutput};
+pub use market_facilitation_index::MarketFacilitationIndex;
 pub use mass_index::MassIndex;
 pub use mcginley_dynamic::McGinleyDynamic;
 pub use median_price::MedianPrice;
 pub use mfi::Mfi;
 pub use mom::Mom;
 pub use natr::Natr;
+pub use nvi::Nvi;
 pub use obv::Obv;
 pub use parkinson::ParkinsonVolatility;
 pub use percent_b::PercentB;
@@ -185,6 +201,7 @@ pub use pgo::Pgo;
 pub use pmo::Pmo;
 pub use ppo::Ppo;
 pub use psar::Psar;
+pub use pvi::Pvi;
 pub use roc::Roc;
 pub use rogers_satchell::RogersSatchellVolatility;
 pub use rsi::Rsi;
@@ -208,17 +225,20 @@ pub use trima::Trima;
 pub use trix::Trix;
 pub use true_range::TrueRange;
 pub use tsi::Tsi;
+pub use tsv::Tsv;
 pub use ttm_squeeze::{TtmSqueeze, TtmSqueezeOutput};
 pub use typical_price::TypicalPrice;
 pub use ulcer_index::UlcerIndex;
 pub use ultimate_oscillator::UltimateOscillator;
 pub use vertical_horizontal_filter::VerticalHorizontalFilter;
 pub use vidya::Vidya;
+pub use volume_oscillator::VolumeOscillator;
 pub use vortex::{Vortex, VortexOutput};
 pub use vpt::VolumePriceTrend;
 pub use vwap::{RollingVwap, Vwap};
 pub use vwap_stddev_bands::{VwapStdDevBands, VwapStdDevBandsOutput};
 pub use vwma::Vwma;
+pub use vzo::Vzo;
 pub use wave_trend::{WaveTrend, WaveTrendOutput};
 pub use weighted_close::WeightedClose;
 pub use williams_r::WilliamsR;