feat: add ffmpeg music player

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/media/musicPlayer.test.ts

@@ -0,0 +1,72 @@
+import { EventEmitter } from "node:events";
+import { PassThrough } from "node:stream";
+import { describe, expect, it, vi } from "vitest";
+import { createMusicPlayer } from "../../src/media/musicPlayer";
+import type { DiscordAudioPlayer } from "../../src/media/mediaTypes";
+
+class FakeProcess extends EventEmitter {
+  stdout = new PassThrough();
+  stderr = new PassThrough();
+  killed = false;
+  kill = vi.fn(() => {
+    this.killed = true;
+    this.emit("close", 0);
+    return true;
+  });
+}
+
+describe("createMusicPlayer", () => {
+  it("spawns ffmpeg as Ogg Opus and passes stdout to Discord", async () => {
+    const proc = new FakeProcess();
+    const spawn = vi.fn(() => proc);
+    const discordPlayer: DiscordAudioPlayer = {
+      isConnected: () => true,
+      playStream: vi.fn(),
+      stop: vi.fn(),
+    };
+    const player = createMusicPlayer({ spawn, discordPlayer });
+
+    const playback = player.play({
+      source: "https://example.com/song.mp3",
+      title: "song.mp3",
+      kind: "url",
+    });
+    proc.emit("close", 0);
+    await playback.done;
+
+    expect(spawn).toHaveBeenCalledWith("ffmpeg", [
+      "-hide_banner",
+      "-loglevel",
+      "warning",
+      "-i",
+      "https://example.com/song.mp3",
+      "-vn",
+      "-acodec",
+      "libopus",
+      "-ar",
+      "48000",
+      "-ac",
+      "2",
+      "-f",
+      "ogg",
+      "pipe:1",
+    ], { stdio: ["ignore", "pipe", "pipe"] });
+    expect(discordPlayer.playStream).toHaveBeenCalledWith(proc.stdout);
+  });
+
+  it("kills ffmpeg and stops Discord playback", () => {
+    const proc = new FakeProcess();
+    const discordPlayer: DiscordAudioPlayer = {
+      isConnected: () => true,
+      playStream: vi.fn(),
+      stop: vi.fn(),
+    };
+    const player = createMusicPlayer({ spawn: vi.fn(() => proc), discordPlayer });
+
+    const playback = player.play({ source: "/tmp/song.ogg", title: "song.ogg", kind: "local" });
+    playback.stop();
+
+    expect(proc.kill).toHaveBeenCalledWith("SIGTERM");
+    expect(discordPlayer.stop).toHaveBeenCalled();
+  });
+});