feat: add Pivots & S/R indicators (B11) (#201)

Adds five support/resistance and pivot indicators, growing the catalog 462 -> 467.

## Indicators
- **CentralPivotRange** (Candle -> struct) — the classic pivot `(H+L+C)/3` flanked by two central levels (TC/BC); range width gauges trending vs balanced days.
- **MurreyMathLines** (Candle -> struct) — T. H. Murrey's eighths grid over a rolling high-low frame; nine levels (0/8 .. 8/8) acting as support/resistance.
- **AndrewsPitchfork** (Candle -> struct) — median line and two parallels projected forward from the last three auto-detected swing pivots (symmetric fractal of half-width `strength`).
- **VolumeWeightedSr** (Candle -> struct) — a band whose edges are the volume-weighted average of recent highs (resistance) and lows (support); falls back to equal weighting when window volume is zero.
- **PivotReversal** (Candle -> f64) — a `+1`/`-1` breakout signal fired on the bar where price closes through the most recently confirmed swing pivot.

## Wiring
Core structs with branch-complete unit tests, Python/Node/WASM bindings, fuzz drives, reference + streaming-vs-batch tests, README + docs counter sync (FAMILIES "Pivots & S/R"), and CHANGELOG entries.

Verified locally: `cargo fmt`, `cargo test -p wickra-core` (3798 lib + 425 doc), `cargo clippy --workspace --all-targets --all-features -D warnings`, `npm run build && npm test` (542), `maturin develop` + `pytest` (891).

docs/README.md

@@ -8,7 +8,7 @@ That includes:
   [Python](https://docs.wickra.org/Quickstart-Python),
   [Node](https://docs.wickra.org/Quickstart-Node), and
   [WASM](https://docs.wickra.org/Quickstart-WASM).
-- A per-indicator deep dive for every one of the **462 indicators** across
+- A per-indicator deep dive for every one of the **467 indicators** across
   the sixteen families (Moving Averages, Momentum Oscillators, Trend &
   Directional, Price Oscillators, Volatility & Bands, Bands & Channels,
   Trailing Stops, Volume, Price Statistics, Ehlers / Cycle DSP, Pivots &