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/probe.ts

@@ -0,0 +1,57 @@
+import { spawn } from "node:child_process";
+
+export interface DroidBinaryStatus {
+  available: boolean;
+  authenticated?: boolean;
+  binaryPath?: string;
+  version?: string;
+  reason?: string;
+  probeDurationMs: number;
+}
+
+async function run(binary: string, args: string[], timeoutMs = 2000): Promise<{ code: number | null; stdout: string; stderr: string }> {
+  return new Promise((resolve) => {
+    const child = spawn(binary, args, { stdio: ["ignore", "pipe", "pipe"] });
+    let stdout = "";
+    let stderr = "";
+    const timer = setTimeout(() => {
+      try { child.kill("SIGKILL"); } catch {
+        // ignore kill errors
+      }
+      resolve({ code: 124, stdout, stderr });
+    }, timeoutMs);
+    child.stdout?.on("data", (c: Buffer) => { stdout += c.toString("utf-8"); });
+    child.stderr?.on("data", (c: Buffer) => { stderr += c.toString("utf-8"); });
+    child.on("error", () => {
+      clearTimeout(timer);
+      resolve({ code: 127, stdout, stderr });
+    });
+    child.on("close", (code) => {
+      clearTimeout(timer);
+      resolve({ code, stdout, stderr });
+    });
+  });
+}
+
+export async function probeDroidBinary(options?: { binaryPath?: string; timeoutMs?: number }): Promise<DroidBinaryStatus> {
+  const startedAt = Date.now();
+  const binaryPath = options?.binaryPath?.trim() || "droid";
+  const timeoutMs = options?.timeoutMs ?? 2000;
+
+  const versionRun = await run(binaryPath, ["--version"], timeoutMs);
+  if (versionRun.code !== 0) {
+    return {
+      available: false,
+      binaryPath,
+      reason: versionRun.code === 124 ? `Probe timed out after ${timeoutMs}ms` : "`droid` not found on PATH",
+      probeDurationMs: Date.now() - startedAt,
+    };
+  }
+
+  return {
+    available: true,
+    binaryPath,
+    version: versionRun.stdout.trim() || undefined,
+    probeDurationMs: Date.now() - startedAt,
+  };
+}