feat(family-08): Pivots & Support/Resistance (7 indicators) (#47)

* feat(family-08): add Classic, Fibonacci, Camarilla, Woodie and DeMark pivots + Williams Fractals + ZigZag

Seven new indicators land the previously empty Pivots & S/R family
(family 08), each implemented in wickra-core with the full Indicator
trait surface (update / reset / warmup_period / is_ready / name),
exposed across Python (PyO3), Node (napi-rs) and WASM (wasm-bindgen)
with the standard streaming + batch APIs, and covered by Rust unit
tests, Python streaming-vs-batch + reference-value tests, Node
streaming-vs-batch tests, the candle-input fuzz target and Rust
microbenchmarks.

- ClassicPivots (7 levels): PP = (H+L+C)/3, three R/S tiers per the
  floor-trader formulas.
- FibonacciPivots (7 levels): PP plus R/S spaced by 0.382 / 0.618 /
  1.000 of the prior range.
- Camarilla (9 levels): Nick Stott's four-tier `C +/- (H - L) * 1.1 /
  {12, 6, 4, 2}` levels.
- WoodiePivots (5 levels): close-weighted PP = (H + L + 2*C) / 4 plus
  two R/S tiers.
- DemarkPivots (3 levels): conditional X sum based on the previous
  bar's open-vs-close relationship.
- WilliamsFractals: five-bar swing detector emitting optional up/down
  fractal prices at the centre of each window.
- ZigZag: percent-threshold swing tracker, non-repainting; emits the
  just-completed extreme and direction on confirmed reversals only.

README family table updated to nine families / 78 indicators;
CHANGELOG records the family-08 addition under [Unreleased].

* fix(family-08 tests): unify MULTI dict to 3-tuple (factory, batch_call, k)

The HEAD-side family-08 test parametrised MULTI[name] as
`(factory, batch_call, output_arity)` so that pivots with arity 3/5/7/9
fit the same harness. Main's entries arrived as 2-tuples; convert them
all to the 3-tuple shape so `make, batch_call, k = MULTI[name]` unpacks
cleanly. Lifecycle test now indexes the tuple instead of destructuring.

* test(zig_zag): tighten flat-oscillation test (drop dead counter branch)

The previous version of `small_oscillations_yield_no_swings` counted
emitted swings, but the assertion proves the counter never increments
so codecov flagged `emitted += 1` as uncovered. Switch to a per-bar
`assert!(...is_none())` — same coverage of the no-swing path, no dead
branch.

bindings/node/__tests__/indicators.test.js

@@ -192,6 +192,14 @@ const multi = {
   TtmSqueeze: { make: () => new wickra.TtmSqueeze(20, 2, 1.5), fields: ['squeeze', 'momentum'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
   FractalChaosBands: { make: () => new wickra.FractalChaosBands(2), fields: ['upper', 'lower'], step: (ind, i) => ind.update(high[i], low[i]), batch: (ind) => ind.batch(high, low) },
   VwapStdDevBands: { make: () => new wickra.VwapStdDevBands(2), fields: ['upper', 'middle', 'lower', 'stddev'], step: (ind, i) => ind.update(high[i], low[i], close[i], volume[i]), batch: (ind) => ind.batch(high, low, close, volume) },
+  // Family 08: Pivots & Support/Resistance
+  ClassicPivots: { make: () => new wickra.ClassicPivots(), fields: ['pp', 'r1', 'r2', 'r3', 's1', 's2', 's3'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
+  FibonacciPivots: { make: () => new wickra.FibonacciPivots(), fields: ['pp', 'r1', 'r2', 'r3', 's1', 's2', 's3'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
+  Camarilla: { make: () => new wickra.Camarilla(), fields: ['pp', 'r1', 'r2', 'r3', 'r4', 's1', 's2', 's3', 's4'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
+  WoodiePivots: { make: () => new wickra.WoodiePivots(), fields: ['pp', 'r1', 'r2', 's1', 's2'], step: (ind, i) => ind.update(high[i], low[i], close[i]), batch: (ind) => ind.batch(high, low, close) },
+  DemarkPivots: { make: () => new wickra.DemarkPivots(), fields: ['pp', 'r1', 's1'], step: (ind, i) => ind.update(open[i], high[i], low[i], close[i]), batch: (ind) => ind.batch(open, high, low, close) },
+  WilliamsFractals: { make: () => new wickra.WilliamsFractals(), fields: ['up', 'down'], step: (ind, i) => ind.update(high[i], low[i]), batch: (ind) => ind.batch(high, low) },
+  ZigZag: { make: () => new wickra.ZigZag(0.02), fields: ['swing', 'direction'], step: (ind, i) => ind.update(high[i], low[i]), batch: (ind) => ind.batch(high, low) },
 };
 
 for (const [name, d] of Object.entries(multi)) {