chore(nests): mv cli/hang-interop → nestsClient/tests/hang-interop

Per maintainer request: the Rust sidecar workspace lives
under the module that owns it, parallel to the upcoming
nestsClient-browser-interop/ harness. The cargo workspace,
Gradle wiring, gitignore, CI YAML, plan docs, and harness
kdoc are all updated. cargo build --release still compiles;
HangInteropTest.amethyst_speaker_to_hang_listener_stereo_440_660
green at the new path.

Note: the live Phase 4 browser-harness agent (worktree
agent-a97a6be483ecee618) was branched from before this move
and references `cli/hang-interop` in its plan-doc imports.
It will need to rebase onto this commit before it pushes;
no code-level conflicts since the agent works exclusively
in nestsClient-browser-interop/ + a new
BrowserInteropTest.kt.

https://claude.ai/code/session_01ERJPUYfdLPwZ99pr5EcEcV

nestsClient/tests/hang-interop/Cargo.toml

@@ -0,0 +1,26 @@
+[workspace]
+resolver = "2"
+members = [
+    "hang-listen",
+    "hang-publish",
+    "udp-loss-shim",
+]
+
+# Phase 1 ships these as stub binaries that compile cleanly but do
+# nothing. Phase 2 fills in real implementations against `hang` /
+# `moq-lite` / `web-transport-quinn`. Versions tracked in REV.
+[workspace.package]
+version = "0.0.1"
+edition = "2024"
+publish = false
+license = "MIT OR Apache-2.0"
+
+[workspace.dependencies]
+anyhow = "1"
+clap = { version = "4", features = ["derive"] }
+tokio = { version = "1", features = ["full"] }
+
+[profile.release]
+opt-level = 3
+lto = "thin"
+strip = true