test(vwap): cover Vwap value()/zero-volume/metadata + RollingVwap getters

Codecov flagged 17 uncovered lines in
crates/wickra-core/src/indicators/vwap.rs (file at 87.94%):

  - Vwap::value() Some branch (line 53) — the only test calling value()
    did so after reset() when sum_v == 0, exercising only the None branch
  - Vwap::update zero-volume early-return `return None;` (line 67) — all
    existing candles carried strictly positive volume
  - Vwap::warmup_period body returning 1 (79-81), Vwap::name body
    returning "VWAP" (87-89) — metadata never queried
  - RollingVwap::period accessor (134-136), RollingVwap::warmup_period
    body (165-167), RollingVwap::name body returning "RollingVWAP"
    (173-175) — same metadata gap on the rolling variant

Add four new tests:

  - cumulative_value_some_branch_after_update drives a single
    non-zero-volume candle then asserts value() == Some(typical_price).
  - cumulative_zero_volume_first_candle_returns_none feeds a candle
    with volume == 0.0, asserts update returns None and is_ready stays
    false, then adds a real candle to confirm the indicator still works.
  - cumulative_metadata asserts warmup_period() == 1 and name() == "VWAP".
  - rolling_accessors_and_metadata asserts period() == 7,
    warmup_period() == 7, name() == "RollingVWAP" on a RollingVwap::new(7).

vwap.rs is now at 141/141 lines, no behavioural change.

crates/wickra-core/src/indicators/vwap.rs

@@ -193,6 +193,42 @@ mod tests {
         assert_relative_eq!(out[2].unwrap(), 20.0, epsilon = 1e-12);
     }
 
+    /// Cover the `Some` branch of `Vwap::value()` (line 53). The only other
+    /// test that calls `value()` is `cumulative_reset_clears_state`, which
+    /// calls it after `reset()` so `sum_v == 0` and the `None` branch fires.
+    #[test]
+    fn cumulative_value_some_branch_after_update() {
+        let mut v = Vwap::new();
+        // typical_price of a flat OHLC bar equals the price itself.
+        v.update(c(42.0, 5.0));
+        assert_relative_eq!(v.value().expect("non-zero volume"), 42.0, epsilon = 1e-12);
+    }
+
+    /// Cover the `return None` early-out inside `Vwap::update` (line 67),
+    /// reached when the running `sum_v` is still 0 after adding the latest
+    /// candle's volume — i.e. the first candle has volume 0. Existing tests
+    /// only use strictly positive volumes, so the early-return never fired.
+    #[test]
+    fn cumulative_zero_volume_first_candle_returns_none() {
+        let mut v = Vwap::new();
+        let out = v.update(c(42.0, 0.0));
+        assert_eq!(out, None);
+        assert!(!v.is_ready());
+        // Adding a non-zero candle afterwards still works as expected.
+        let out2 = v.update(c(10.0, 4.0));
+        assert_relative_eq!(out2.expect("now warmed"), 10.0, epsilon = 1e-12);
+    }
+
+    /// Cover the cumulative `Vwap` Indicator-impl metadata: `warmup_period`
+    /// (lines 79-81) and `name` (lines 87-89). Existing tests inspected
+    /// only the numeric output, never the metadata surface.
+    #[test]
+    fn cumulative_metadata() {
+        let v = Vwap::new();
+        assert_eq!(v.warmup_period(), 1);
+        assert_eq!(v.name(), "VWAP");
+    }
+
     #[test]
     fn cumulative_vwap_weighted() {
         // Two candles: 10@1 and 20@3 -> (10*1 + 20*3) / (1+3) = 70/4 = 17.5
@@ -202,6 +238,18 @@ mod tests {
         assert_relative_eq!(out[1].unwrap(), 17.5, epsilon = 1e-12);
     }
 
+    /// Cover the `RollingVwap` accessors and metadata: `period`
+    /// (lines 134-136), `warmup_period` (165-167), `name` (173-175).
+    /// Existing rolling tests called `update`/`batch`/`reset`/`is_ready`
+    /// only, never queried the configuration or metadata.
+    #[test]
+    fn rolling_accessors_and_metadata() {
+        let v = RollingVwap::new(7).unwrap();
+        assert_eq!(v.period(), 7);
+        assert_eq!(v.warmup_period(), 7);
+        assert_eq!(v.name(), "RollingVWAP");
+    }
+
     #[test]
     fn rolling_vwap_window_slides() {
         let candles = vec![c(10.0, 1.0), c(20.0, 1.0), c(30.0, 1.0), c(40.0, 1.0)];