feat: universal agent support — MCP server + REST OpenAPI

- dex serve --mcp: MCP protocol for Claude Desktop, Cursor, Windsurf, Cline
- REST API with OpenAPI 3.0 schema at /api/openapi.json
- POST /api/tools/call for direct tool execution
- POST /api/chat for stateless agent chat
- Fix package name in fs test

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: 2 people

.claude/settings.local.json

@@ -0,0 +1,5 @@
+{
+  "enabledPlugins": {
+    "superpowers@claude-plugins-official": true
+  }
+}

src/utils/__tests__/fs.test.ts

@@ -80,7 +80,7 @@ describe("fs utils", () => {
       // Use this project's own package.json
       const result = await readPackageJson(process.cwd());
       expect(result).not.toBeNull();
-      expect(result!.name).toBe("dex-cli");
+      expect(result!.name).toBe("dexai-cli");
     });
 
     it("should return null when no package.json exists", async () => {