feat(bd-2vw): display raw lore data in debug view

Add DebugView component to show raw lore status data for visual
verification that the data pipeline works end-to-end:
- Frontend -> Tauri IPC -> Rust backend -> lore CLI -> parsed data

New files:
- src/components/DebugView.tsx - Debug component with health indicator
- src/hooks/useLoreData.ts - TanStack Query hook for lore status
- tests/components/DebugView.test.tsx - Component tests
- tests/hooks/useLoreData.test.ts - Hook tests

Modified:
- src/App.tsx - Add QueryClientProvider wrapper
- src/stores/nav-store.ts - Add 'debug' ViewId
- src/components/AppShell.tsx - Add Debug nav tab and view routing
- tests/components/AppShell.test.tsx - Update tests for new nav

tests/hooks/useLoreData.test.ts

@@ -0,0 +1,97 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { renderHook, waitFor } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { createElement } from "react";
+import { useLoreData } from "@/hooks/useLoreData";
+import { setMockResponse, resetMocks } from "../mocks/tauri-api";
+
+function createWrapper() {
+  const queryClient = new QueryClient({
+    defaultOptions: {
+      queries: {
+        retry: false,
+      },
+    },
+  });
+  return function Wrapper({ children }: { children: React.ReactNode }) {
+    return createElement(QueryClientProvider, { client: queryClient }, children);
+  };
+}
+
+describe("useLoreData", () => {
+  beforeEach(() => {
+    resetMocks();
+  });
+
+  it("returns loading state initially", () => {
+    const { result } = renderHook(() => useLoreData(), {
+      wrapper: createWrapper(),
+    });
+
+    expect(result.current.isLoading).toBe(true);
+    expect(result.current.data).toBeUndefined();
+  });
+
+  it("returns lore status data on success", async () => {
+    const mockStatus = {
+      last_sync: "2026-02-26T12:00:00Z",
+      is_healthy: true,
+      message: "Lore is healthy",
+      summary: {
+        open_issues: 5,
+        authored_mrs: 2,
+        reviewing_mrs: 3,
+      },
+    };
+
+    setMockResponse("get_lore_status", mockStatus);
+
+    const { result } = renderHook(() => useLoreData(), {
+      wrapper: createWrapper(),
+    });
+
+    await waitFor(() => {
+      expect(result.current.isLoading).toBe(false);
+    });
+
+    expect(result.current.data).toEqual(mockStatus);
+    expect(result.current.error).toBeNull();
+  });
+
+  it("returns error state when IPC fails", async () => {
+    setMockResponse("get_lore_status", Promise.reject(new Error("IPC failed")));
+
+    const { result } = renderHook(() => useLoreData(), {
+      wrapper: createWrapper(),
+    });
+
+    await waitFor(() => {
+      expect(result.current.isLoading).toBe(false);
+    });
+
+    expect(result.current.error).toBeTruthy();
+    expect(result.current.data).toBeUndefined();
+  });
+
+  it("returns unhealthy status", async () => {
+    const mockStatus = {
+      last_sync: null,
+      is_healthy: false,
+      message: "lore not configured",
+      summary: null,
+    };
+
+    setMockResponse("get_lore_status", mockStatus);
+
+    const { result } = renderHook(() => useLoreData(), {
+      wrapper: createWrapper(),
+    });
+
+    await waitFor(() => {
+      expect(result.current.isLoading).toBe(false);
+    });
+
+    expect(result.current.data?.is_healthy).toBe(false);
+    expect(result.current.data?.summary).toBeNull();
+  });
+});