feat(microstructure): trade-sign autocorrelation, PIN, Hasbrouck information share (B15) (#212)

## B15 Microstructure — three new indicators (485 → 488)

| Indicator | Input | Output | Notes |
|-----------|-------|--------|-------|
| `TradeSignAutocorrelation` | `Trade` | `f64` ∈ [-1,1] | lag-1 autocorrelation of the signed aggressor (order-flow persistence) |
| `Pin` | `Trade` | `f64` ∈ [0,1] | probability of informed trading from rolling buy/sell imbalance (EKOP single-window estimator); `name()` = `"PIN"` |
| `HasbrouckInformationShare` | `(f64, f64)` | `f64` ∈ [0,1] | variance-ratio proxy for each venue's share of price discovery |

### Wiring
- Core structs + full unit tests (every branch).
- Hand-written Python/Node/WASM bindings for the two `Trade`-input indicators (precedent `TradeImbalance`); `node_pair_indicator!` / `wasm_pair_indicator!` macro bindings + hand Python pyclass for the pairwise Hasbrouck (precedent `RollingCorrelation`).
- Fuzz drives added to `indicator_update_trade.rs` and `indicator_update_pair.rs`.
- Dedicated Python + Node streaming-vs-batch and reference tests; Hasbrouck in the `PAIR` registry.
- README counter (3 spots) + `docs/README.md` + `FAMILIES` assert bumped to 488.

### Verify (all green, local)
- `cargo test -p wickra-core --lib`: 3991 passed
- `cargo test -p wickra-core --doc`: 438 passed
- `cargo clippy --workspace --all-targets --all-features -- -D warnings`: clean
- node: 561 passed · pytest: 926 passed

bindings/wasm/src/lib.rs

@@ -563,6 +563,11 @@ wasm_pair_indicator!(
     "BetaNeutralSpread",
     wc::BetaNeutralSpread
 );
+wasm_pair_indicator!(
+    WasmHasbrouckInformationShare,
+    "HasbrouckInformationShare",
+    wc::HasbrouckInformationShare
+);
 
 // ---------- PairSpreadZScore (two params) ----------
 
@@ -9279,6 +9284,66 @@ impl WasmTradeImbalance {
     }
 }
 
+// Trade-sign autocorrelation carries a `period` parameter, so it is hand-written.
+#[wasm_bindgen(js_name = TradeSignAutocorrelation)]
+pub struct WasmTradeSignAutocorrelation {
+    inner: wc::TradeSignAutocorrelation,
+}
+
+#[wasm_bindgen(js_class = TradeSignAutocorrelation)]
+impl WasmTradeSignAutocorrelation {
+    #[wasm_bindgen(constructor)]
+    pub fn new(period: usize) -> Result<WasmTradeSignAutocorrelation, JsError> {
+        Ok(Self {
+            inner: wc::TradeSignAutocorrelation::new(period).map_err(map_err)?,
+        })
+    }
+    pub fn update(&mut self, price: f64, size: f64, is_buy: bool) -> Result<Option<f64>, JsError> {
+        Ok(self.inner.update(build_trade(price, size, is_buy)?))
+    }
+    pub fn reset(&mut self) {
+        self.inner.reset();
+    }
+    #[wasm_bindgen(js_name = isReady)]
+    pub fn is_ready(&self) -> bool {
+        self.inner.is_ready()
+    }
+    #[wasm_bindgen(js_name = warmupPeriod)]
+    pub fn warmup_period(&self) -> usize {
+        self.inner.warmup_period()
+    }
+}
+
+// PIN carries a `window` parameter, so it is hand-written.
+#[wasm_bindgen(js_name = Pin)]
+pub struct WasmPin {
+    inner: wc::Pin,
+}
+
+#[wasm_bindgen(js_class = Pin)]
+impl WasmPin {
+    #[wasm_bindgen(constructor)]
+    pub fn new(window: usize) -> Result<WasmPin, JsError> {
+        Ok(Self {
+            inner: wc::Pin::new(window).map_err(map_err)?,
+        })
+    }
+    pub fn update(&mut self, price: f64, size: f64, is_buy: bool) -> Result<Option<f64>, JsError> {
+        Ok(self.inner.update(build_trade(price, size, is_buy)?))
+    }
+    pub fn reset(&mut self) {
+        self.inner.reset();
+    }
+    #[wasm_bindgen(js_name = isReady)]
+    pub fn is_ready(&self) -> bool {
+        self.inner.is_ready()
+    }
+    #[wasm_bindgen(js_name = warmupPeriod)]
+    pub fn warmup_period(&self) -> usize {
+        self.inner.warmup_period()
+    }
+}
+
 // Order Flow Imbalance: order-book input with a `period` parameter.
 #[wasm_bindgen(js_name = OrderFlowImbalance)]
 pub struct WasmOrderFlowImbalance {