feat(FN-3328): refactor droid-cli into compatibility shim backed by fusion-

Merged FN-3328: Refactored the droid integration by converting `droid-cli` into a lightweight compatibility shim that delegates to `fusion-plugin-droid-runtime`, reducing droid-cli by ~5,400 lines of code while moving the actual runtime logic into the plugin scaffold. Updated the plugin loader to al

Fusion-Task-Id: FN-3328

plugins/fusion-plugin-droid-runtime/src/__tests__/probe.test.ts

@@ -1,22 +1,61 @@
-import { describe, expect, it, vi } from "vitest";
+import { describe, expect, it, vi, beforeEach } from "vitest";
 import { EventEmitter } from "node:events";
 import { PassThrough } from "node:stream";
 
+const spawnMock = vi.hoisted(() => vi.fn());
+
 vi.mock("node:child_process", () => ({
-  spawn: vi.fn(() => {
-    const proc = new EventEmitter() as any;
-    proc.stdout = new PassThrough();
-    proc.stderr = new PassThrough();
-    queueMicrotask(() => proc.emit("error", Object.assign(new Error("not found"), { code: "ENOENT" })));
-    return proc;
-  }),
+  spawn: spawnMock,
 }));
 
 import { probeDroidBinary } from "../probe.js";
 
 describe("probeDroidBinary", () => {
+  beforeEach(() => {
+    spawnMock.mockReset();
+  });
+
   it("returns unavailable when binary is missing", async () => {
+    spawnMock.mockImplementationOnce(() => {
+      const proc = new EventEmitter() as any;
+      proc.stdout = new PassThrough();
+      proc.stderr = new PassThrough();
+      queueMicrotask(() => proc.emit("error", Object.assign(new Error("not found"), { code: "ENOENT" })));
+      return proc;
+    });
+
     const result = await probeDroidBinary({ timeoutMs: 10 });
     expect(result.available).toBe(false);
+    expect(result.reason).toContain("not found");
+  });
+
+  it("returns available and version on success", async () => {
+    spawnMock.mockImplementationOnce(() => {
+      const proc = new EventEmitter() as any;
+      proc.stdout = new PassThrough();
+      proc.stderr = new PassThrough();
+      queueMicrotask(() => {
+        proc.stdout.write("droid 1.2.3\n");
+        proc.emit("close", 0);
+      });
+      return proc;
+    });
+
+    const result = await probeDroidBinary();
+    expect(result.available).toBe(true);
+    expect(result.version).toBe("droid 1.2.3");
+  });
+
+  it("uses custom binary path", async () => {
+    spawnMock.mockImplementationOnce(() => {
+      const proc = new EventEmitter() as any;
+      proc.stdout = new PassThrough();
+      proc.stderr = new PassThrough();
+      queueMicrotask(() => proc.emit("close", 1));
+      return proc;
+    });
+
+    await probeDroidBinary({ binaryPath: "/custom/droid" });
+    expect(spawnMock).toHaveBeenCalledWith("/custom/droid", ["--version"], expect.anything());
   });
 });