feat: add 9 Risk / Performance indicators (B18) (#218)

Adds nine risk/performance metrics to the existing **Risk / Performance** family, all consuming a per-period return series (`f64` in, `f64` out). Indicator count **498 → 507**.

## Indicators

Single-param (`new(period)`, macro bindings):
- **SterlingRatio** — mean return over average drawdown of the equity curve.
- **BurkeRatio** — return over root-sum-squared drawdowns.
- **MartinRatio** — Ulcer Performance Index; return over RMS percentage drawdown.
- **TailRatio** — 95th percentile over the absolute 5th percentile return.
- **KRatio** — Kestner; equity-curve OLS slope over the standard error of that slope.
- **CommonSenseRatio** — tail ratio times gain-to-pain.
- **GainToPainRatio** — sum of returns over the sum of absolute losses.

Multi-param (hand-written Python/Node bindings, variadic WASM macro):
- **UpsidePotentialRatio** — `new(period, mar)`; upside mean over downside deviation (Sortino philosophy).
- **M2Measure** — `new(period, risk_free, benchmark_stddev)`; Modigliani M², Sharpe rescaled into benchmark return units.

## Touchpoints
Core modules + unit tests, `mod.rs`/`lib.rs` wiring, Python/Node/WASM bindings (`index.d.ts`/`index.js` regenerated), fuzz drive lines, Python `SCALAR` registry + Node factories, CHANGELOG, and the indicator counters.

## Verification
- `cargo test -p wickra-core --lib` — 4149 passed
- `cargo test -p wickra-core --doc` — 457 passed
- `cargo clippy --workspace --all-targets --all-features -- -D warnings` — clean
- `npm test` (node) — 577 passed
- `pytest` (python) — 947 passed

README.md

@@ -1,5 +1,5 @@
 <p align="center">
-  <a href="https://wickra.org"><img src="https://raw.githubusercontent.com/wickra-lib/.github/main/profile/wickra-banner.webp?v=498" alt="Wickra — streaming-first technical indicators" width="100%"></a>
+  <a href="https://wickra.org"><img src="https://raw.githubusercontent.com/wickra-lib/.github/main/profile/wickra-banner.webp?v=507" alt="Wickra — streaming-first technical indicators" width="100%"></a>
 </p>
 
 [![CI](https://github.com/wickra-lib/wickra/actions/workflows/ci.yml/badge.svg)](https://github.com/wickra-lib/wickra/actions/workflows/ci.yml)
@@ -48,7 +48,7 @@ Full documentation lives at **[docs.wickra.org](https://docs.wickra.org)**:
   [Node](https://docs.wickra.org/Quickstart-Node),
   [WASM](https://docs.wickra.org/Quickstart-WASM).
 - **Indicators** — a per-indicator deep dive (formula, parameters, warmup) for
-  every one of the 498 indicators; start at the
+  every one of the 507 indicators; start at the
   [indicators overview](https://docs.wickra.org/Indicators-Overview).
 - **Reference** — [warmup periods](https://docs.wickra.org/Warmup-Periods),
   [streaming vs batch](https://docs.wickra.org/Streaming-vs-Batch),
@@ -66,7 +66,7 @@ an afterthought — **live, tick-by-tick data** — without giving up the breadt
 a full batch library, and without making you reimplement your indicators four
 times to get there.
 
-- **The biggest streaming-native catalogue, period.** 498 indicators across 24
+- **The biggest streaming-native catalogue, period.** 507 indicators across 24
   families — candlesticks, harmonic & chart patterns, market profile, market
   breadth, Renko/Kagi/Point&Figure bars, Ehlers DSP cycles, risk/performance
   metrics — every single one updating in **O(1) per tick**. TA-Lib ships ~150 and
@@ -77,7 +77,7 @@ times to get there.
 - **Correct by construction, not by hope.** Every `update` validates its input,
   runs a real warmup, and returns an `Option` so a single bad tick can't silently
   poison state. `batch == streaming` is **bit-exact, fuzzed and 100 %-line-covered
-  for all 498 indicators**.
+  for all 507 indicators**.
 - **Orders of magnitude faster where it counts.** In streaming Wickra is **11–56×**
   faster than the only other incremental peer and **thousands of times** faster
   than recompute-on-every-tick libraries. On batch it wins several rows outright
@@ -95,7 +95,7 @@ Every other library forces one of those compromises. Wickra doesn't:
 
 | Library          | Install     | Streaming   | Languages                   | Indicators | Active |
 |------------------|-------------|-------------|-----------------------------|-----------:|--------|
-| **★&nbsp;Wickra**| **clean**   | **yes, O(1)** | **Python · Node · WASM · Rust** | **498** | **yes** |
+| **★&nbsp;Wickra**| **clean**   | **yes, O(1)** | **Python · Node · WASM · Rust** | **507** | **yes** |
 | kand             | clean       | yes         | Python · WASM · Rust        |       ~60  | yes    |
 | ta-rs            | clean       | yes         | Rust only                   |       ~30  | stale  |
 | yata             | clean       | partial     | Rust only                   |       ~35  | yes    |
@@ -128,7 +128,7 @@ Full tables (Rust + Python, streaming + batch) and how to reproduce them live in
 
 ## Indicators
 
-498 streaming-first indicators across twenty-four families. Every one passes the
+507 streaming-first indicators across twenty-four families. Every one passes the
 `batch == streaming` equivalence test, reference-value tests, and reset
 semantics tests. Each has a per-indicator deep dive (formula, parameters,
 warmup) at [docs.wickra.org](https://docs.wickra.org/Indicators-Overview).
@@ -237,7 +237,7 @@ A Python live-trading example using the public `websockets` package lives at
 ```
 wickra/
 ├── crates/
-│   ├── wickra-core/         core engine + all 498 indicators
+│   ├── wickra-core/         core engine + all 507 indicators
 │   ├── wickra/              top-level facade crate (publishes on crates.io) + benches/
 │   ├── wickra-data/         CSV reader, tick aggregator, live exchange feeds
 │   └── wickra-bench/        internal cross-library benchmark harness (not published)