feat: Family 03 MACD & Price Oscillators — APO / AO-Hist / CFO / Zero-Lag MACD / Elder Impulse / STC (#41)

* feat(apo): add Absolute Price Oscillator

EMA(close, fast) - EMA(close, slow). Like MACD without the signal EMA.
Defaults to (fast = 12, slow = 26); fast must be strictly less than
slow.

Touchpoints: apo.rs + mod.rs + lib.rs re-export, PyApo + __init__.py
+ test_new_indicators SCALAR + test_known_values flat reference,
ApoNode + index.d.ts/index.js + indicators.test.js factory + reference,
WasmApo via scalar macro, scalar-fuzz target, README + CHANGELOG.

* fix(apo): add PyApo + ApoNode + WasmApo bindings missed from ec269d8

The previous APO commit (ec269d8) only registered APO in the Python
__init__.py / Node index.js / Node index.d.ts / fuzz / tests / docs.
The actual PyApo pyclass, ApoNode napi class, and WasmApo wasm class
edits silently no-op'd because the underlying lib.rs files had been
touched by a branch switch between Read and Edit. The bindings were
therefore advertising APO from the Python module / Node package /
WASM module but not actually exposing it.

Fix: insert PyApo block + add_class call in bindings/python/src/lib.rs,
ApoNode block in bindings/node/src/lib.rs, WasmApo macro line in
bindings/wasm/src/lib.rs. cargo test workspace stays at 615 (no new
tests added; the existing test_known_values + indicators.test.js
references would have failed at import once the bindings rebuilt
without these classes).

* feat(ao-histogram): add Awesome Oscillator Histogram

AO - SMA(AO, sma_period). A configurable variant of the existing
AcceleratorOscillator (which fixes fast=5, slow=34, sma=5).
Three parameters; defaults match Bill Williams' Accelerator.

Touchpoints: awesome_oscillator_histogram.rs + mod.rs + lib.rs
re-export, PyAoHist + __init__.py + test_new_indicators CANDLE_SCALAR
+ test_known_values flat reference, AwesomeOscillatorHistogramNode +
index.d.ts/index.js + indicators.test.js factory + reference,
WasmAoHist, candle-fuzz target, README + CHANGELOG.

* feat(cfo): add Chande Forecast Oscillator

100 * (close - LinReg(close, period)) / close. Positive when close
overshoots the linear forecast, negative when it undershoots. Holds
the previous value if the close is zero (percentage form undefined).
Single param period (default 14).

Touchpoints: cfo.rs + mod.rs + lib.rs re-export, PyCfo + __init__.py
+ test_new_indicators SCALAR + test_known_values linear reference,
CfoNode + index.d.ts/index.js + indicators.test.js factory + reference,
WasmCfo via scalar macro, scalar-fuzz target, README + CHANGELOG.

* fix(cfo): add WasmCfo binding missed from 733afd9

* feat(zero-lag-macd): add Zero-Lag MACD

Classic MACD topology with ZLEMA substituted for EMA everywhere:
faster reaction to trend changes at the cost of slightly noisier
readings. Multi-output ZeroLagMacdOutput { macd, signal, histogram }.
Three parameters (fast = 12, slow = 26, signal = 9); fast must be
strictly less than slow.

Touchpoints: zero_lag_macd.rs + mod.rs + lib.rs re-export, PyZeroLagMacd
+ __init__.py + test_new_indicators MULTI + test_known_values flat
reference, ZeroLagMacdNode + ZeroLagMacdValue + index.d.ts/index.js +
indicators.test.js multi factory + reference, WasmZeroLagMacd, scalar
fuzz with hand-rolled drive (multi-output bypasses the f64-only
helper), README + CHANGELOG.

* feat(elder-impulse): add Alexander Elder Impulse System

Tri-state momentum gauge: +1 (green/buy) when EMA trend and MACD
histogram both rise, -1 (red/sell) when both fall, 0 (blue/neutral)
on disagreement. Four parameters (ema_period, macd_fast, macd_slow,
macd_signal); defaults (13, 12, 26, 9) match Elder.

Internally feeds both branches on every input so they warm in parallel;
needs one bar past the slowest branch to seed direction state.

Touchpoints: elder_impulse.rs + mod.rs + lib.rs re-export, PyElderImpulse
+ __init__.py + test_new_indicators SCALAR + test_known_values neutral
reference, ElderImpulseNode + index.d.ts/index.js + indicators.test.js
factory + reference, WasmElderImpulse via scalar macro, scalar-fuzz
target, README + CHANGELOG.

* feat(stc): add Schaff Trend Cycle

Doug Schaff's doubly-Stochastic-smoothed MACD. Bounded [0, 100]
reading that reacts faster than MACD by extracting the percentile of
MACD within a recent window, half-EMA-smoothing it, and re-stochasing
the smoothed series. Four parameters (fast = 23, slow = 50,
schaff_period = 10, factor = 0.5); fast must be strictly less than
slow and factor must lie in (0, 1].

Output clamped to [0, 100] to absorb floating-point rounding. The
stochastic stages clamp to 0 when their rolling range collapses (flat
input or perfectly monotone trend), so a flat series settles
deterministically at 0 after warmup.

Touchpoints: stc.rs + mod.rs + lib.rs re-export, PyStc + __init__.py
+ test_new_indicators SCALAR + test_known_values flat reference,
StcNode + index.d.ts/index.js + indicators.test.js factory + reference,
WasmStc via scalar macro, scalar-fuzz target, README + CHANGELOG.

* fix(stc): rename last_stc -> last_value to satisfy clippy

* ci: Retry setup-node and setup-python on CDN flakes

Setup-node on Windows runners and setup-python across all OSes
occasionally fail with a silent hang or 5xx mid-download ("Attempting
to download 18..." → fail in <1s) — pure upstream CDN flake. The fix
ran on this branch's previous merge commit (24e723f) had to be
re-triggered manually via `gh run rerun --failed`.

Wrap both setup actions with continue-on-error and a follow-up retry
step that waits 30s and re-runs the same setup. The retry only fires
when the first attempt failed (steps.<id>.outcome == 'failure'), so a
green setup costs nothing extra. The retry uses the identical pinned
SHA so we still get supply-chain verification on both attempts.

Applied to ci.yml (Python matrix and Node matrix). release.yml has
the same setup-node / setup-python steps but is rarely re-run, so
the existing manual rerun pattern stays sufficient for now.

* test(zero-lag-macd): Fix MULTI dict shape mismatch + cover warmup_period

ZeroLagMACD was registered in the Python MULTI dict (which asserts a
(n, 2) batch shape) but actually emits (n, 3) — macd, signal,
histogram — like MACD. Moved out into its own standalone test
test_zero_lag_macd_streaming_matches_batch (3-tuple shape), and
included in the lifecycle sweep. Mirrors the existing Alligator
pattern for 3-output candle indicators.

Also adds a unit test for ZeroLagMacd::warmup_period that pins both
the (12, 26, 9) classic case and a small-period config — these four
lines were the codecov/patch miss on PR 41.

fuzz/fuzz_targets/indicator_update.rs

@@ -15,11 +15,11 @@
 
 use libfuzzer_sys::fuzz_target;
 use wickra_core::{
-    Alma, BatchExt, BollingerBands, Cmo, ConnorsRsi, Coppock, Dema, Dpo, Ema, Frama,
-    HistoricalVolatility, Hma, Indicator, Jma, Kama, Kst, LaguerreRsi, LinRegAngle, LinRegSlope,
-    LinearRegression, MacdIndicator, McGinleyDynamic, Mom, Pmo, Ppo, Roc, Rsi, Sma, Smma, StdDev,
-    StochRsi, T3, Tema, Trima, Trix, Tsi, UlcerIndex, VerticalHorizontalFilter, Vidya, Wma, ZScore,
-    Zlema,
+    Alma, Apo, BatchExt, BollingerBands, Cfo, Cmo, ConnorsRsi, Coppock, Dema, Dpo, ElderImpulse,
+    Ema, Frama, HistoricalVolatility, Hma, Indicator, Jma, Kama, Kst, LaguerreRsi, LinRegAngle,
+    LinRegSlope, LinearRegression, MacdIndicator, McGinleyDynamic, Mom, Pmo, Ppo, Roc, Rsi, Sma,
+    Smma, Stc, StdDev, StochRsi, T3, Tema, Trima, Trix, Tsi, UlcerIndex, VerticalHorizontalFilter,
+    Vidya, Wma, ZScore, ZeroLagMacd, Zlema,
 };
 
 /// Drive a single streaming + batch run through one scalar indicator. Marked
@@ -67,6 +67,10 @@ fuzz_target!(|data: Vec<f64>| {
     drive(|| StochRsi::new(14, 14).unwrap(), &data);
     drive(|| Dpo::new(14).unwrap(), &data);
     drive(|| Ppo::new(12, 26).unwrap(), &data);
+    drive(|| Apo::new(12, 26).unwrap(), &data);
+    drive(|| Cfo::new(14).unwrap(), &data);
+    drive(|| ElderImpulse::classic(), &data);
+    drive(|| Stc::classic(), &data);
     drive(|| Coppock::new(14, 11, 10).unwrap(), &data);
     drive(|| StdDev::new(14).unwrap(), &data);
     drive(|| UlcerIndex::new(14).unwrap(), &data);
@@ -89,6 +93,16 @@ fuzz_target!(|data: Vec<f64>| {
         let _ = Kst::classic().batch(&data);
     }
 
+    // Zero-Lag MACD shares MACD's multi-output topology, so it gets the
+    // same hand-rolled streaming + batch drive as classic MACD below.
+    {
+        let mut z = ZeroLagMacd::classic();
+        for &x in &data {
+            let _ = z.update(x);
+        }
+        let _ = ZeroLagMacd::classic().batch(&data);
+    }
+
     // MACD and Bollinger Bands have non-`f64` outputs, so they cannot use the
     // generic `drive` helper above. Streaming + batch are still both exercised.
     {

fuzz/fuzz_targets/indicator_update_candle.rs

@@ -24,7 +24,8 @@
 use libfuzzer_sys::fuzz_target;
 use wickra_core::{
     AcceleratorOscillator, Adl, Adx, Alligator, Aroon, AroonOscillator, Atr, AtrTrailingStop,
-    AwesomeOscillator, BalanceOfPower, BatchExt, Candle, Cci, ChaikinMoneyFlow, ChaikinOscillator,
+    AwesomeOscillator, AwesomeOscillatorHistogram, BalanceOfPower, BatchExt, Candle, Cci,
+    ChaikinMoneyFlow, ChaikinOscillator,
     ChaikinVolatility, ChandeKrollStop, ChandelierExit, ChoppinessIndex, Donchian, EaseOfMovement,
     Evwma, ForceIndex, Indicator, Inertia, Keltner, MassIndex, MedianPrice, Mfi, Natr, Obv, Pgo,
     Psar, RollingVwap, Rvi, Smi,
@@ -103,6 +104,10 @@ fuzz_target!(|data: Vec<f64>| {
     drive(|| Smi::classic(), &candles);
     drive(|| WilliamsR::new(14).unwrap(), &candles);
     drive(|| AwesomeOscillator::new(5, 34).unwrap(), &candles);
+    drive(
+        || AwesomeOscillatorHistogram::new(5, 34, 5).unwrap(),
+        &candles,
+    );
     drive(|| AcceleratorOscillator::new(5, 34, 5).unwrap(), &candles);
     drive(|| UltimateOscillator::new(7, 14, 28).unwrap(), &candles);
     drive(BalanceOfPower::new, &candles);