feat: add Ichimoku & Charts deepening (B13, 5 indicators) (#207)

B13 of the family-deepening roadmap — five alternative-chart indicators (474 -> 479), all in the **Ichimoku & Charts** family.

- **Smoothed Heikin-Ashi** (`candle -> struct {open, high, low, close}`) — a Heikin-Ashi candle computed from EMA-smoothed OHLC.
- **Heikin-Ashi Oscillator** (`candle -> f64`) — the HA body (`ha_close - ha_open`), optionally EMA-smoothed, as a zero-line oscillator.
- **Three Line Break** (`candle -> f64`) — line-break ("kakushi") chart trend direction; reverses only when the close breaks the extreme of the last N lines. Distinct from the candlestick `ThreeLineStrike`.
- **Equivolume** (`candle -> struct {height, width}`) — a box whose height is the bar range and width is volume-relative.
- **CandleVolume** (`candle -> struct {body, width}`) — a candle whose body is close-minus-open and width is volume-relative.

All bindings hand-written (3 struct-output + 2 candle-input-with-open / non-period-ctor). Wiring complete across core, Python, Node, WASM, fuzz, tests, README + docs counter (479) and CHANGELOG. Verified: core 3915 + doc 432, clippy clean, node 554, python 913.

bindings/node/index.d.ts

@@ -385,6 +385,20 @@ export interface HeikinAshiValue {
   low: number
   close: number
 }
+export interface SmoothedHeikinAshiValue {
+  open: number
+  high: number
+  low: number
+  close: number
+}
+export interface EquivolumeValue {
+  height: number
+  width: number
+}
+export interface CandleVolumeValue {
+  body: number
+  width: number
+}
 export interface ValueAreaValue {
   poc: number
   vah: number
@@ -3362,6 +3376,51 @@ export declare class HeikinAshi {
   isReady(): boolean
   warmupPeriod(): number
 }
+export type HeikinAshiOscillatorNode = HeikinAshiOscillator
+export declare class HeikinAshiOscillator {
+  constructor(period: number)
+  update(open: number, high: number, low: number, close: number): number | null
+  batch(open: Array<number>, high: Array<number>, low: Array<number>, close: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type ThreeLineBreakNode = ThreeLineBreak
+export declare class ThreeLineBreak {
+  constructor(lines: number)
+  update(high: number, low: number, close: number): number | null
+  batch(high: Array<number>, low: Array<number>, close: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type SmoothedHeikinAshiNode = SmoothedHeikinAshi
+export declare class SmoothedHeikinAshi {
+  constructor(period: number)
+  update(open: number, high: number, low: number, close: number): SmoothedHeikinAshiValue | null
+  batch(open: Array<number>, high: Array<number>, low: Array<number>, close: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type EquivolumeNode = Equivolume
+export declare class Equivolume {
+  constructor(period: number)
+  update(high: number, low: number, volume: number): EquivolumeValue | null
+  batch(high: Array<number>, low: Array<number>, volume: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
+export type CandleVolumeNode = CandleVolume
+export declare class CandleVolume {
+  constructor(period: number)
+  update(open: number, close: number, volume: number): CandleVolumeValue | null
+  batch(open: Array<number>, close: Array<number>, volume: Array<number>): Array<number>
+  reset(): void
+  isReady(): boolean
+  warmupPeriod(): number
+}
 export type ValueAreaNode = ValueArea
 export declare class ValueArea {
   constructor(period: number, binCount: number, valueAreaPct: number)