feat(FN-3332): add droid runtime plugin with event bridge and process manag

The merge delivers a new `fusion-plugin-droid-runtime` plugin providing a full MCP server and runtime adapter for droid-based agents, with event bridging, process management, tool mapping, and a prompt builder. It also adds agent delegation and org hierarchy tools to the pi extension, while fixing a

Fusion-Task-Id: FN-3332

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

@@ -0,0 +1,22 @@
+import { describe, expect, it, vi } from "vitest";
+import { EventEmitter } from "node:events";
+import { PassThrough } from "node:stream";
+
+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;
+  }),
+}));
+
+import { probeDroidBinary } from "../probe.js";
+
+describe("probeDroidBinary", () => {
+  it("returns unavailable when binary is missing", async () => {
+    const result = await probeDroidBinary({ timeoutMs: 10 });
+    expect(result.available).toBe(false);
+  });
+});