feat(#41): implement Widget/HUD system

- BaseWidget wrapper with loading/error states
- WidgetRegistry for central widget management
- WidgetGrid with react-grid-layout integration
- TasksWidget, CalendarWidget, QuickCaptureWidget
- useLayouts hooks for layout persistence
- Comprehensive test suite (TDD approach)

apps/web/src/components/widgets/__tests__/WidgetRegistry.test.tsx

@@ -0,0 +1,91 @@
+/**
+ * Widget Registry Tests
+ * Following TDD - write tests first!
+ */
+
+import { describe, it, expect } from "vitest";
+import { widgetRegistry } from "../WidgetRegistry";
+import { TasksWidget } from "../TasksWidget";
+import { CalendarWidget } from "../CalendarWidget";
+import { QuickCaptureWidget } from "../QuickCaptureWidget";
+
+describe("WidgetRegistry", () => {
+  it("should have a registry of widgets", () => {
+    expect(widgetRegistry).toBeDefined();
+    expect(typeof widgetRegistry).toBe("object");
+  });
+
+  it("should include TasksWidget in registry", () => {
+    expect(widgetRegistry.TasksWidget).toBeDefined();
+    expect(widgetRegistry.TasksWidget.component).toBe(TasksWidget);
+  });
+
+  it("should include CalendarWidget in registry", () => {
+    expect(widgetRegistry.CalendarWidget).toBeDefined();
+    expect(widgetRegistry.CalendarWidget.component).toBe(CalendarWidget);
+  });
+
+  it("should include QuickCaptureWidget in registry", () => {
+    expect(widgetRegistry.QuickCaptureWidget).toBeDefined();
+    expect(widgetRegistry.QuickCaptureWidget.component).toBe(QuickCaptureWidget);
+  });
+
+  it("should have correct metadata for TasksWidget", () => {
+    const tasksWidget = widgetRegistry.TasksWidget;
+    expect(tasksWidget.name).toBe("TasksWidget");
+    expect(tasksWidget.displayName).toBe("Tasks");
+    expect(tasksWidget.description).toBeDefined();
+    expect(tasksWidget.defaultWidth).toBeGreaterThan(0);
+    expect(tasksWidget.defaultHeight).toBeGreaterThan(0);
+    expect(tasksWidget.minWidth).toBeGreaterThan(0);
+    expect(tasksWidget.minHeight).toBeGreaterThan(0);
+  });
+
+  it("should have correct metadata for CalendarWidget", () => {
+    const calendarWidget = widgetRegistry.CalendarWidget;
+    expect(calendarWidget.name).toBe("CalendarWidget");
+    expect(calendarWidget.displayName).toBe("Calendar");
+    expect(calendarWidget.description).toBeDefined();
+    expect(calendarWidget.defaultWidth).toBeGreaterThan(0);
+    expect(calendarWidget.defaultHeight).toBeGreaterThan(0);
+  });
+
+  it("should have correct metadata for QuickCaptureWidget", () => {
+    const quickCaptureWidget = widgetRegistry.QuickCaptureWidget;
+    expect(quickCaptureWidget.name).toBe("QuickCaptureWidget");
+    expect(quickCaptureWidget.displayName).toBe("Quick Capture");
+    expect(quickCaptureWidget.description).toBeDefined();
+    expect(quickCaptureWidget.defaultWidth).toBeGreaterThan(0);
+    expect(quickCaptureWidget.defaultHeight).toBeGreaterThan(0);
+  });
+
+  it("should export getWidgetByName helper", async () => {
+    const { getWidgetByName } = await import("../WidgetRegistry");
+    expect(typeof getWidgetByName).toBe("function");
+  });
+
+  it("getWidgetByName should return correct widget", async () => {
+    const { getWidgetByName } = await import("../WidgetRegistry");
+    const widget = getWidgetByName("TasksWidget");
+    expect(widget).toBeDefined();
+    expect(widget?.component).toBe(TasksWidget);
+  });
+
+  it("getWidgetByName should return undefined for invalid name", async () => {
+    const { getWidgetByName } = await import("../WidgetRegistry");
+    const widget = getWidgetByName("InvalidWidget");
+    expect(widget).toBeUndefined();
+  });
+
+  it("should export getAllWidgets helper", async () => {
+    const { getAllWidgets } = await import("../WidgetRegistry");
+    expect(typeof getAllWidgets).toBe("function");
+  });
+
+  it("getAllWidgets should return array of all widgets", async () => {
+    const { getAllWidgets } = await import("../WidgetRegistry");
+    const widgets = getAllWidgets();
+    expect(Array.isArray(widgets)).toBe(true);
+    expect(widgets.length).toBeGreaterThanOrEqual(3);
+  });
+});