test(dashboard): add getProject mock to node-routes CentralCore mock

The PATCH /api/projects/:id route handler now reads central.getProject
before attempting updates/assignments. The CentralCore mock in
node-routes.test.ts didn't include that method, so the route threw and
returned 500 instead of 200. Add the stub.

Fixes 2 failing tests in node-routes.test.ts (assigns/unassigns nodeId
PATCH cases).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/src/__tests__/node-routes.test.ts

@@ -36,6 +36,15 @@ vi.mock("@fusion/core", async () => {
       unregisterNode: mockUnregisterNode,
       checkNodeHealth: mockCheckNodeHealth,
       updateProject: mockUpdateProject,
+      getProject: vi.fn(async (id: string) => ({
+        id,
+        name: "Project",
+        path: "/tmp/project",
+        status: "active",
+        isolationMode: "in-process",
+        createdAt: "2026-01-01T00:00:00.000Z",
+        updatedAt: "2026-01-01T00:00:00.000Z",
+      })),
       assignProjectToNode: mockAssignProjectToNode,
       unassignProjectFromNode: mockUnassignProjectFromNode,
       getLocalMeshSnapshot: mockGetLocalMeshSnapshot,