feat(neswire): open the audio server

Captures a session's audio and hands it to the transport over a local socket.
Third component in, imported as a tree from `nestrilabs/neswire` on the same
terms as the previous two.

Wired to the workspace, `nesprotocol` by path. 4 tests pass.

`bin/hub-stub.rs` is a stand-in for the transport's listener, which is what lets
this be developed and tested without the rest of a box existing. It names the
transport by its old name, and is left for the rename commit along with the two
in the compositor.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/neswire/src/main.rs

@@ -0,0 +1,58 @@
+mod encoder;
+mod sink;
+
+use clap::Parser;
+
+#[derive(Parser, Debug)]
+struct Args {
+    /// Path for the audio IPC socket (neswire → nestri-guest-hub)
+    #[arg(
+        long,
+        env = "NESWIRE_IPC_PATH",
+        default_value = "/tmp/nestri-audio.sock"
+    )]
+    ipc_path: String,
+
+    /// Output channels: 2, 6, or 8
+    #[arg(long, env = "NESWIRE_CHANNELS", default_value_t = 2)]
+    channels: u32,
+
+    /// Packet duration in ms (5, 10..)
+    #[arg(long, env = "NESWIRE_PACKET_DURATION_MS", default_value_t = 5)]
+    packet_duration_ms: u32,
+
+    /// Bitrate per channel in kbps
+    #[arg(long, env = "NESWIRE_BITRATE_PER_CHANNEL", default_value_t = 64)]
+    bitrate_per_channel: u32,
+}
+
+fn main() -> anyhow::Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .init();
+
+    let args = Args::parse();
+
+    let sample_rate = 48_000u32;
+    let frame_size = (sample_rate * args.packet_duration_ms) / 1000;
+
+    let (tx, rx) = crossbeam_channel::bounded::<Vec<f32>>(256);
+
+    let encoder_config = encoder::EncoderConfig {
+        channels: args.channels,
+        sample_rate,
+        frame_size,
+        ipc_path: args.ipc_path,
+        bitrate_per_channel: args.bitrate_per_channel,
+    };
+
+    std::thread::spawn(move || {
+        if let Err(e) = encoder::run(encoder_config, rx) {
+            tracing::error!("encoder thread died: {e:#}");
+        }
+    });
+
+    sink::run(sample_rate, args.channels, frame_size, tx)?;
+
+    Ok(())
+}