feat: Family 05 Bands & Channels - 11 new price-envelope indicators (#43)

* feat(bands-channels): add Family 05 with 11 indicators

Eleven price-envelope overlays organised into a new "Bands & Channels"
family, exposed across all four bindings (Rust core, Python, Node, WASM)
plus fuzz/test/bench/docs coverage:

- MaEnvelope - SMA centerline with fixed-percent envelope (the oldest
  band overlay still in regular use).
- AccelerationBands (Price Headley) - momentum-biased bands that widen
  with the bar's relative range (H - L) / (H + L).
- StarcBands (Stoller Average Range Channel) - SMA(close) +/- k*ATR;
  Keltner's SMA-centerline sibling.
- AtrBands - close-anchored envelope of width k*ATR; the standard
  volatility-targeting stop/target band.
- HurstChannel - SMA centerline wrapped by the rolling high-low range
  (Brian Millard / Hurst-cycle channel).
- LinRegChannel - rolling OLS endpoint +/- k * population stddev of the
  residuals; dispersion about the trend rather than the mean.
- StandardErrorBands - regression line +/- k * OLS standard error
  (denominator n - 2) for prediction-interval bands.
- DoubleBollinger (Kathy Lien) - two concentric BB envelopes
  (typically +/- 1 sigma and +/- 2 sigma) for the zone-partition setup.
- TtmSqueeze (John Carter) - BB-inside-KC squeeze flag paired with a
  detrended-close linear-regression momentum reading.
- FractalChaosBands - Bill Williams 5-bar fractal high/low envelope.
- VwapStdDevBands - cumulative VWAP with volume-weighted population
  standard deviation bands.

Each indicator ships:
- Core impl with the full Indicator trait, classic() where applicable,
  and unit tests (rejects_zero_period / multiplier, accessors, flat
  market, monotonic ordering, batch == streaming, reset, plus
  algebraically verifiable reference values).
- Python PyO3 binding with multi-column NumPy batch (PyArray2).
- Node napi binding with #[napi(object)] struct + interleaved flat
  batch.
- WASM wasm-bindgen binding via Object/Reflect for update +
  Float64Array for batch.
- Fuzz coverage in fuzz_targets/indicator_update{,_candle}.rs.
- Python streaming-vs-batch parametric test + reference test.
- Node streaming-vs-interleaved-batch test + reference test.
- Criterion microbench under crates/wickra/benches/indicators.rs.

README family table, README indicator-count line, and CHANGELOG
Unreleased entry updated: indicator total rises from 71 to 82 across
nine families. Wiki pages are updated in a separate commit in the
wickra.wiki repo.

* test(acceleration-bands): cover sum_hl==0 zero-price guard

Exercises line 104 (`0.0` branch of the `sum_hl == 0.0` guard) which
was the last patch-coverage miss on the family-05 PR. `Candle::new`
accepts a fully-zero bar so the branch is reachable in principle —
add a degenerate-candle unit test to hit it.

crates/wickra-core/src/lib.rs

@@ -44,20 +44,24 @@ pub mod indicators;
 
 pub use error::{Error, Result};
 pub use indicators::{
-    AcceleratorOscillator, Adl, Adx, AdxOutput, Alligator, AlligatorOutput, Alma, Apo, Aroon,
-    AroonOscillator, AroonOutput, Atr, AtrTrailingStop, AwesomeOscillator,
-    AwesomeOscillatorHistogram, BalanceOfPower, BollingerBands, BollingerBandwidth,
-    BollingerOutput, Cci, Cfo, ChaikinMoneyFlow, ChaikinOscillator, ChaikinVolatility,
-    ChandeKrollStop, ChandeKrollStopOutput, ChandelierExit, ChandelierExitOutput, ChoppinessIndex,
-    Cmo, ConnorsRsi, Coppock, Dema, Donchian, DonchianOutput, Dpo, EaseOfMovement, ElderImpulse,
-    Ema, Evwma, ForceIndex, Frama, GarmanKlassVolatility, HistoricalVolatility, Hma, Inertia, Jma,
-    Kama, Keltner, KeltnerOutput, Kst, KstOutput, LaguerreRsi, LinRegAngle, LinRegSlope,
-    LinearRegression, MacdIndicator, MacdOutput, MassIndex, McGinleyDynamic, MedianPrice, Mfi, Mom,
-    Natr, Obv, ParkinsonVolatility, PercentB, Pgo, Pmo, Ppo, Psar, Roc, RogersSatchellVolatility,
-    RollingVwap, Rsi, Rvi, RviVolatility, Sma, Smi, Smma, Stc, StdDev, StochRsi, Stochastic,
-    StochasticOutput, SuperTrend, SuperTrendOutput, Tema, Trima, Trix, TrueRange, Tsi,
-    TypicalPrice, UlcerIndex, UltimateOscillator, VerticalHorizontalFilter, Vidya,
-    VolumePriceTrend, Vortex, VortexOutput, Vwap, Vwma, WeightedClose, WilliamsR, Wma,
+    AccelerationBands, AccelerationBandsOutput, AcceleratorOscillator, Adl, Adx, AdxOutput,
+    Alligator, AlligatorOutput, Alma, Apo, Aroon, AroonOscillator, AroonOutput, Atr, AtrBands,
+    AtrBandsOutput, AtrTrailingStop, AwesomeOscillator, AwesomeOscillatorHistogram, BalanceOfPower,
+    BollingerBands, BollingerBandwidth, BollingerOutput, Cci, Cfo, ChaikinMoneyFlow,
+    ChaikinOscillator, ChaikinVolatility, ChandeKrollStop, ChandeKrollStopOutput, ChandelierExit,
+    ChandelierExitOutput, ChoppinessIndex, Cmo, ConnorsRsi, Coppock, Dema, Donchian,
+    DonchianOutput, DoubleBollinger, DoubleBollingerOutput, Dpo, EaseOfMovement, ElderImpulse, Ema,
+    Evwma, ForceIndex, FractalChaosBands, FractalChaosBandsOutput, Frama, GarmanKlassVolatility,
+    HistoricalVolatility, Hma, HurstChannel, HurstChannelOutput, Inertia, Jma, Kama, Keltner,
+    KeltnerOutput, Kst, KstOutput, LaguerreRsi, LinRegAngle, LinRegChannel, LinRegChannelOutput,
+    LinRegSlope, LinearRegression, MaEnvelope, MaEnvelopeOutput, MacdIndicator, MacdOutput,
+    MassIndex, McGinleyDynamic, MedianPrice, Mfi, Mom, Natr, Obv, ParkinsonVolatility, PercentB,
+    Pgo, Pmo, Ppo, Psar, Roc, RogersSatchellVolatility, RollingVwap, Rsi, Rvi, RviVolatility, Sma,
+    Smi, Smma, StandardErrorBands, StandardErrorBandsOutput, StarcBands, StarcBandsOutput, Stc,
+    StdDev, StochRsi, Stochastic, StochasticOutput, SuperTrend, SuperTrendOutput, Tema, Trima,
+    Trix, TrueRange, Tsi, TtmSqueeze, TtmSqueezeOutput, TypicalPrice, UlcerIndex,
+    UltimateOscillator, VerticalHorizontalFilter, Vidya, VolumePriceTrend, Vortex, VortexOutput,
+    Vwap, VwapStdDevBands, VwapStdDevBandsOutput, Vwma, WeightedClose, WilliamsR, Wma,
     YangZhangVolatility, ZScore, ZeroLagMacd, ZeroLagMacdOutput, Zlema, T3,
 };
 pub use ohlcv::{Candle, Tick};