feat(FN-3109): add Docker connectivity service and target selector UI

This merge adds Docker connectivity management to Fusion (FN-3109), introducing a Docker client service in `@fusion/core` with typed interfaces for daemon connection configuration (host, socket path, TLS). The dashboard gains a `DockerTargetSelector` component for choosing between local socket and T

Fusion-Task-Id: FN-3109

packages/dashboard/app/hooks/__tests__/useDockerTargets.test.ts

@@ -0,0 +1,40 @@
+import { act, renderHook } from "@testing-library/react";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { useDockerTargets } from "../useDockerTargets";
+
+describe("useDockerTargets", () => {
+  beforeEach(() => {
+    vi.restoreAllMocks();
+    global.fetch = vi.fn() as unknown as typeof fetch;
+  });
+
+  it("loads contexts", async () => {
+    vi.mocked(fetch).mockResolvedValue({ ok: true, json: async () => [{ name: "default", isCurrentContext: true }] } as Response);
+    const { result } = renderHook(() => useDockerTargets());
+    await act(async () => {
+      await result.current.loadContexts();
+    });
+    expect(result.current.contexts).toHaveLength(1);
+  });
+
+  it("tests connection", async () => {
+    vi.mocked(fetch).mockResolvedValue({ ok: true, json: async () => ({ success: true, isLocalDaemon: true }) } as Response);
+    const { result } = renderHook(() => useDockerTargets());
+    await act(async () => {
+      await result.current.testConnection({ host: "tcp://1.2.3.4:2376" });
+    });
+    expect(fetch).toHaveBeenCalledWith(
+      "/api/docker/test-connection",
+      expect.objectContaining({ method: "POST" }),
+    );
+  });
+
+  it("checks local docker", async () => {
+    vi.mocked(fetch).mockResolvedValue({ ok: true, json: async () => ({ available: true, version: "24.0" }) } as Response);
+    const { result } = renderHook(() => useDockerTargets());
+    await act(async () => {
+      const response = await result.current.checkLocalDocker();
+      expect(response.available).toBe(true);
+    });
+  });
+});