F5: add PPO, DPO and Coppock Curve price oscillators

Completes the F5 family (Price oscillators) end to end:

- Rust core: ppo.rs (Percentage Price Oscillator — MACD as a percentage
  of the slow EMA), dpo.rs (Detrended Price Oscillator — shifted price
  minus its SMA), coppock.rs (Coppock Curve — WMA of two summed ROCs).
  Each with a full Indicator impl, runnable doctest and reference /
  constant-series / warmup / reset / batch==streaming / non-finite tests.
- Python: PyPpo / PyDpo / PyCoppock PyO3 classes + module registration
  + .pyi stubs (defaults PPO=(12,26), DPO=20, Coppock=(14,11,10)).
- Node: DpoNode via the scalar macro, explicit PpoNode and CoppockNode;
  index.d.ts and index.js updated.
- WASM: WasmDpo / WasmPpo / WasmCoppock via the scalar macro.
- Wiki: Indicator-Ppo/Dpo/Coppock.md plus rows in Indicators-Overview.md
  and entries in Home.md.

cargo fmt + clippy (core/wickra/data/wasm/node) clean; 300 core tests,
25 data tests and 42 doctests green.

bindings/wasm/src/lib.rs

@@ -84,6 +84,9 @@ wasm_scalar_indicator!(WasmCmo, "CMO", wc::Cmo, period: usize);
 wasm_scalar_indicator!(WasmTsi, "TSI", wc::Tsi, long: usize, short: usize);
 wasm_scalar_indicator!(WasmPmo, "PMO", wc::Pmo, smoothing1: usize, smoothing2: usize);
 wasm_scalar_indicator!(WasmStochRsi, "StochRSI", wc::StochRsi, rsi_period: usize, stoch_period: usize);
+wasm_scalar_indicator!(WasmDpo, "DPO", wc::Dpo, period: usize);
+wasm_scalar_indicator!(WasmPpo, "PPO", wc::Ppo, fast: usize, slow: usize);
+wasm_scalar_indicator!(WasmCoppock, "Coppock", wc::Coppock, roc_long: usize, roc_short: usize, wma_period: usize);
 
 // ---------- KAMA (three params) ----------