feat(nests): T16 Phase 2 — JVM Opus + Rust↔Rust E2E interop test

Lands the test-side audio codec + the first end-to-end interop
scenario through the harness:

- JvmOpusEncoder / JvmOpusDecoder via club.minnced:opus-java 1.1.1
  (JNA bindings + bundled libopus.so / .dylib / .dll natives).
  Verified by JvmOpusRoundTripTest — sine 440 Hz survives encode →
  decode with FFT peak preserved + ZCR within 5%.
- SineWaveAudioCapture now paces to real time (20 ms / frame)
  rather than running open-loop. Mirrors how a real microphone
  source blocks on hardware; without it the broadcaster floods
  the relay at compute speed.
- HangInteropTest.rust_hang_publish_to_rust_hang_listener_round_trip_440
  drives hang-publish + hang-listen as subprocesses through the
  harness's moq-relay and asserts FFT peak / ZCR / sample-count
  on the decoded PCM. Verified green on Linux x86_64.
- hang-publish gains --track-name (default "audio/data" matching
  Amethyst's MoqLiteNestsListener.AUDIO_TRACK) and decouples
  --relay-url from --broadcast so the URL path can be the
  namespace and the broadcast can be a relative announce suffix.
- hang-listen's tail "cancelled" error is treated as EOF after
  any frames have been collected, so a clean publisher shutdown
  no longer surfaces as exit=1.

The forward-direction I1 scenario (Amethyst Kotlin speaker → hang
listener) is still gated by an open Amethyst-side wire issue: the
audio uni stream delivers Group control headers but no frame
payloads. Documented in
nestsClient/plans/2026-05-06-cross-stack-interop-test-results.md
with concrete pickup steps for a follow-up session.

https://claude.ai/code/session_01ERJPUYfdLPwZ99pr5EcEcV

nestsClient/build.gradle.kts

@@ -74,6 +74,17 @@ kotlin {
                 implementation(libs.kotlin.test)
                 implementation(libs.kotlinx.coroutines.test)
                 implementation(libs.secp256k1.kmp.jni.jvm)
+                // JNA bindings + bundled libopus.so used by the cross-stack
+                // interop tests (T16). The Android targets keep their
+                // existing `MediaCodecOpusEncoder/Decoder`; only JVM
+                // tests need a host-side codec, and `club.minnced:opus-java`
+                // ships natives for linux-x86-64 / aarch64 / darwin / win32.
+                // No Android dependency is added. opus-java-api declares
+                // JNA as runtime-scope; Kotlin needs it at compile time to
+                // resolve the `tomp2p.opuswrapper.Opus extends com.sun.jna.Library`
+                // supertype, so pull it explicitly.
+                implementation("club.minnced:opus-java:1.1.1")
+                implementation("net.java.dev.jna:jna:5.14.0")
             }
         }