feat(wave2): add @mosaic/openclaw-context plugin to monorepo

- OpenClaw → OpenBrain context engine plugin migrated from mosaic/openclaw-openbrain-context
- Depends on @mosaic/types workspace:*
- Typecheck passing

plugins/openclaw-context/tests/register.test.ts

@@ -0,0 +1,30 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { OPENBRAIN_CONTEXT_ENGINE_ID, register } from "../src/index.js";
+
+describe("plugin register()", () => {
+  it("registers the openbrain context engine factory", async () => {
+    const registerContextEngine = vi.fn();
+
+    register({
+      registerContextEngine,
+      pluginConfig: {
+        baseUrl: "https://brain.example.com",
+        apiKey: "secret",
+      },
+      logger: {
+        debug: vi.fn(),
+        info: vi.fn(),
+        warn: vi.fn(),
+        error: vi.fn(),
+      },
+    });
+
+    expect(registerContextEngine).toHaveBeenCalledTimes(1);
+    const [id, factory] = registerContextEngine.mock.calls[0] as [string, () => Promise<unknown> | unknown];
+    expect(id).toBe(OPENBRAIN_CONTEXT_ENGINE_ID);
+
+    const engine = await factory();
+    expect(engine).toHaveProperty("info.id", OPENBRAIN_CONTEXT_ENGINE_ID);
+  });
+});