feat(patterns): add the Harmonic Patterns family (8 XABCD detectors) (#169)

## Summary

Adds a new **Harmonic Patterns** indicator family (counter 359 → 367, families 22 → 23) — the second half of the A4 roadmap item, following the Chart Patterns family in #166.

Eight Fibonacci-ratio detectors built on the shared swing-pivot tracker (`indicators::pattern_swing`) plus two new helpers there — `xabcd` (reads the last five pivots as X-A-B-C-D) and `ratios_in` (checks a list of `(value, low, high)` Fibonacci windows in one expression, no multi-line `&&` coverage gaps). Each consumes candles and emits the uniform pattern sign convention — `+1.0` bullish (terminal point D a swing low), `-1.0` bearish (D a swing high), `0.0` otherwise, never `None`. Parameter-free, with the Fibonacci windows documented as constants per detector.

## Detectors

| Indicator | Defining ratio |
|-----------|----------------|
| `Abcd` | four-point AB=CD (BC retraces AB, CD ≈ AB) |
| `Gartley` | AD/XA ≈ 0.786 |
| `Butterfly` | AD/XA ∈ 1.27–1.618 (extended D) |
| `Bat` | AD/XA ≈ 0.886, shallow B |
| `Crab` | AD/XA ≈ 1.618 (deepest D) |
| `Shark` | expansion AB, AD/XA 0.886–1.13 |
| `Cypher` | BC on XA, CD/XC ≈ 0.786 |
| `ThreeDrives` | two symmetric extension drives |

## Touchpoints

Core modules + `FAMILIES` group/assert, crate root re-exports, Python/Node/WASM bindings via the candle-pattern macros (Node `index.d.ts`/`index.js` regenerated), the candle fuzz target (`// --- Harmonic Patterns ---` section), Python reference + `CANDLE_SCALAR` registry tests and the Node candle-scalar factory, README catalogue counter + banner cache-buster + family table row + family-count word, `docs/README.md` counter, and the changelog.

## Verification

- `cargo test -p wickra-core --lib` — 2966 passed
- `cargo test -p wickra-core --doc` — 335 passed
- `cargo clippy --workspace --all-targets --all-features -- -D warnings` — clean
- Node `npm run build && npm test` — 444 passed
- Python `maturin develop --release` + `pytest` — 748 passed

Every detector branch is unit-tested, including a bullish and a bearish match per pattern to cover both output arms, plus an out-of-ratio non-match. Fibonacci windows use standard harmonic-trading ranges with documented tolerance bands.

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

@@ -0,0 +1,152 @@
+//! Cypher harmonic pattern.
+
+use crate::indicators::pattern_swing::{ratios_in, xabcd, SwingTracker, SWING_THRESHOLD};
+use crate::ohlcv::Candle;
+use crate::traits::Indicator;
+
+/// Cypher — a 5-point (X-A-B-C-D) harmonic pattern whose C leg is measured
+/// against XA (not AB) and whose D retraces the XC leg by `0.786`:
+///
+/// ```text
+/// AB / XA ∈ [0.382, 0.618]
+/// BC / XA ∈ [1.13, 1.414]  (C extends beyond A, measured on XA)
+/// CD / XC ∈ [0.74, 0.83]   (≈ 0.786 retracement of XC — the D completion)
+/// ```
+///
+/// Output is `+1.0` (bullish, D a swing low), `-1.0` (bearish, D a swing high),
+/// or `0.0`; never `None`. See `crates/wickra-core/src/indicators/cypher.rs`.
+#[derive(Debug, Clone)]
+pub struct Cypher {
+    swing: SwingTracker,
+    has_emitted: bool,
+}
+
+impl Cypher {
+    /// Construct a new Cypher detector.
+    pub const fn new() -> Self {
+        Self {
+            swing: SwingTracker::new(SWING_THRESHOLD, 5),
+            has_emitted: false,
+        }
+    }
+}
+
+impl Default for Cypher {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Indicator for Cypher {
+    type Input = Candle;
+    type Output = f64;
+
+    fn update(&mut self, candle: Candle) -> Option<f64> {
+        self.has_emitted = true;
+        if !self.swing.update(candle) {
+            return Some(0.0);
+        }
+        let pivots = self.swing.pivots();
+        if pivots.len() < 5 {
+            return Some(0.0);
+        }
+        let p = xabcd(pivots);
+        let xa = (p.a - p.x).abs();
+        let ab = (p.b - p.a).abs();
+        let bc = (p.c - p.b).abs();
+        let xc = (p.c - p.x).abs();
+        let cd = (p.d - p.c).abs();
+        let matched = ratios_in(&[
+            (ab / xa, 0.382, 0.618),
+            (bc / xa, 1.13, 1.414),
+            (cd / xc, 0.74, 0.83),
+        ]);
+        if matched {
+            return Some(if p.bullish { 1.0 } else { -1.0 });
+        }
+        Some(0.0)
+    }
+
+    fn reset(&mut self) {
+        self.swing.reset();
+        self.has_emitted = false;
+    }
+
+    fn warmup_period(&self) -> usize {
+        6
+    }
+
+    fn is_ready(&self) -> bool {
+        self.has_emitted
+    }
+
+    fn name(&self) -> &'static str {
+        "Cypher"
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::indicators::pattern_swing::candles_for_pivots;
+    use crate::traits::BatchExt;
+
+    fn run(pivots: &[f64]) -> Vec<f64> {
+        let mut indicator = Cypher::new();
+        candles_for_pivots(pivots)
+            .into_iter()
+            .map(|c| indicator.update(c).unwrap())
+            .collect()
+    }
+
+    #[test]
+    fn accessors_and_metadata() {
+        let indicator = Cypher::new();
+        assert_eq!(indicator.name(), "Cypher");
+        assert_eq!(indicator.warmup_period(), 6);
+        assert!(!indicator.is_ready());
+        assert!(!Cypher::default().is_ready());
+    }
+
+    #[test]
+    fn bullish_cypher_is_plus_one() {
+        let out = run(&[150.0, 100.0, 140.0, 120.0, 168.0, 114.55]);
+        assert_eq!(*out.last().unwrap(), 1.0);
+        assert!(out[..out.len() - 1].iter().all(|&x| x == 0.0));
+    }
+
+    #[test]
+    fn bearish_cypher_is_minus_one() {
+        let out = run(&[150.0, 110.0, 130.0, 82.0, 135.45]);
+        assert_eq!(*out.last().unwrap(), -1.0);
+    }
+
+    #[test]
+    fn out_of_ratio_does_not_trigger() {
+        let out = run(&[150.0, 100.0, 140.0, 110.0, 135.0, 105.0]);
+        assert_eq!(*out.last().unwrap(), 0.0);
+    }
+
+    #[test]
+    fn reset_clears_state() {
+        let mut indicator = Cypher::new();
+        for c in candles_for_pivots(&[150.0, 100.0, 140.0]) {
+            let _ = indicator.update(c);
+        }
+        indicator.reset();
+        assert!(!indicator.is_ready());
+        let c = Candle::new(99.5, 100.0, 99.5, 99.5, 1.0, 0).unwrap();
+        assert_eq!(indicator.update(c), Some(0.0));
+    }
+
+    #[test]
+    fn batch_equals_streaming() {
+        let candles = candles_for_pivots(&[150.0, 100.0, 140.0, 120.0, 168.0, 114.55]);
+        let mut a = Cypher::new();
+        let mut b = Cypher::new();
+        assert_eq!(
+            a.batch(&candles),
+            candles.iter().map(|x| b.update(*x)).collect::<Vec<_>>()
+        );
+    }
+}