fix(wzp-native): Oboe ResultWithValue has no value_or, unfold explicitly

cc-rs build of oboe_bridge.cpp failed at cfa9ff6 because the Oboe
ResultWithValue<T> template returned by getXRunCount() does not have
a .value_or(T) method — only .value(). Replace with an explicit
bool-conversion + .value() guard that yields -1 on error.

crates/wzp-native/cpp/oboe_bridge.cpp

@@ -211,7 +211,8 @@ public:
         calls++;
         if ((calls % 50) == 0) {
             int state = (int)stream->getState();
-            int xruns = stream->getXRunCount().value_or(-1);
+            auto xrunRes = stream->getXRunCount();
+            int xruns = xrunRes ? xrunRes.value() : -1;
             LOGI("playout heartbeat: calls=%llu nonempty=%llu numFrames=%d ring_avail_read=%d to_read=%d underrun_frames=%llu total_played_real=%llu state=%d xruns=%d",
                  (unsigned long long)calls, (unsigned long long)nonempty_calls,
                  numFrames, avail, to_read,