feat(family-15): add 17 risk/performance metrics (#54)

* feat(family-15): add 17 risk/performance metrics

Implements Family 15 pragmatically as standard `Indicator`s instead of a
separate `wickra-metrics` crate. Input is scalar `f64` per bar — period
return, equity sample, or per-trade P&L depending on the metric.

Scalar `Indicator<f64>` (14):
- SharpeRatio(period, risk_free)
- SortinoRatio(period, mar)
- CalmarRatio(period)
- OmegaRatio(period, threshold)
- MaxDrawdown(period)          — rolling, peak-to-trough
- AverageDrawdown(period)
- DrawdownDuration             — cumulative, bars under water (u32 output)
- PainIndex(period)
- ValueAtRisk(period, confidence)
- ConditionalValueAtRisk(period, confidence)
- ProfitFactor(period)
- GainLossRatio(period)
- RecoveryFactor               — cumulative, net return / max drawdown
- KellyCriterion(period)

Two-series `Indicator<(f64, f64)>` for (asset, benchmark) returns (3):
- TreynorRatio(period, risk_free)
- InformationRatio(period)
- Alpha(period, risk_free)     — Jensen / CAPM

Touchpoints:
- 17 new files under `crates/wickra-core/src/indicators/`.
- `mod.rs` + `lib.rs` re-exports.
- Python bindings (`bindings/python/src/lib.rs`, `__init__.py`).
- Node bindings (`bindings/node/src/lib.rs`, `index.js`).
- WASM bindings (`bindings/wasm/src/lib.rs`).
- Fuzz: scalar metrics appended to `indicator_update.rs`; new
  `indicator_update_pair.rs` fuzz target for `(f64, f64)` indicators.
- Python tests: SCALAR + new PAIR parameter lists in `test_new_indicators.py`,
  reference-value cases in `test_known_values.py`.
- Node tests: scalar factories + new pair-factory block in
  `bindings/node/__tests__/indicators.test.js`.
- Benches: 5 Family-15 benches added in `crates/wickra/benches/indicators.rs`.
- Docs: README family-table row + counter (71 -> 88), CHANGELOG entry under
  [Unreleased].

Note: Family 12 (statistik-regression, PR #51) introduces
`node_pair_indicator!` and `wasm_pair_indicator!` macros for Pearson /
Beta / Spearman. Family 15 needs the same pair-input pattern but Family 12
is not yet in main, so the three pair wrappers below are written by hand
in this PR. When PR #51 lands, the trivial merge-conflict is resolved by
keeping the macros from Family 12 and re-using them for Treynor / IR /
Alpha (drop the three handwritten wrappers).

cargo check --workspace --all-features: green.

* fix(family-15): satisfy clippy doc_markdown / if_not_else / digit_grouping

* fix(family-15): unused TreynorRatio import, duplicate pairFactories, _eq_nan inf handling

* fix(family-15): node eq() handles matching infinities for ratio indicators

* test(family-15): cover cold paths flagged by codecov patch

fuzz/fuzz_targets/indicator_update_candle.rs

@@ -25,18 +25,18 @@ use libfuzzer_sys::fuzz_target;
 use wickra_core::{
     AccelerationBands, AcceleratorOscillator, AdOscillator, Adl, Adx, Adxr, Alligator,
     AnchoredVwap, Aroon, AroonOscillator, Atr, AtrBands, AtrTrailingStop, AwesomeOscillator,
-    AwesomeOscillatorHistogram, BalanceOfPower, BatchExt, Camarilla, Candle, Cci,
-    ChaikinMoneyFlow, ChaikinOscillator, ChaikinVolatility, ChandeKrollStop, ChandelierExit,
-    ChoppinessIndex, ClassicPivots, DemandIndex, DemarkPivots, Doji, Donchian, DonchianStop,
-    EaseOfMovement, Engulfing, Evwma, FibonacciPivots, ForceIndex, FractalChaosBands,
-    GarmanKlassVolatility, Hammer, HangingMan, Harami, HeikinAshi, HiLoActivator, HurstChannel, Ichimoku,
-    Indicator, Inertia, InitialBalance, InvertedHammer, Keltner, Kvo, MarketFacilitationIndex,
-    Marubozu, MassIndex, MedianPrice, Mfi, MorningEveningStar, Natr, Nvi, Obv, OpeningRange,
+    AwesomeOscillatorHistogram, BalanceOfPower, BatchExt, Camarilla, Candle, Cci, ChaikinMoneyFlow,
+    ChaikinOscillator, ChaikinVolatility, ChandeKrollStop, ChandelierExit, ChoppinessIndex,
+    ClassicPivots, DemandIndex, DemarkPivots, Doji, Donchian, DonchianStop, EaseOfMovement,
+    Engulfing, Evwma, FibonacciPivots, ForceIndex, FractalChaosBands, GarmanKlassVolatility,
+    Hammer, HangingMan, Harami, HeikinAshi, HiLoActivator, HurstChannel, Ichimoku, Indicator,
+    Inertia, InitialBalance, InvertedHammer, Keltner, Kvo, MarketFacilitationIndex, Marubozu,
+    MassIndex, MedianPrice, Mfi, MorningEveningStar, Natr, Nvi, Obv, OpeningRange,
     ParkinsonVolatility, Pgo, PiercingDarkCloud, Psar, Pvi, RogersSatchellVolatility, RollingVwap,
     Rvi, Rwi, ShootingStar, Smi, SpinningTop, StarcBands, Stochastic, SuperTrend, TdCombo,
-    TdCountdown, TdDeMarker, TdDifferential, TdLines, TdOpen, TdPressure, TdRangeProjection,
-    TdRei, TdRiskLevel, TdSequential, TdSetup, ThreeInside, ThreeOutside, ThreeSoldiersOrCrows,
-    TrueRange, Tsv, TtmSqueeze, Tweezer, TypicalPrice, UltimateOscillator, ValueArea, VoltyStop,
+    TdCountdown, TdDeMarker, TdDifferential, TdLines, TdOpen, TdPressure, TdRangeProjection, TdRei,
+    TdRiskLevel, TdSequential, TdSetup, ThreeInside, ThreeOutside, ThreeSoldiersOrCrows, TrueRange,
+    Tsv, TtmSqueeze, Tweezer, TypicalPrice, UltimateOscillator, ValueArea, VoltyStop,
     VolumeOscillator, VolumePriceTrend, Vortex, Vwap, VwapStdDevBands, Vwma, Vzo, WaveTrend,
     WeightedClose, WilliamsFractals, WilliamsR, WoodiePivots, YangZhangVolatility, YoyoExit,
     ZigZag,