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

src/hooks/useLoreData.ts

@@ -0,0 +1,48 @@
+/**
+ * Hook for fetching lore status data via Tauri IPC.
+ *
+ * Uses TanStack Query for caching and state management.
+ * The data can be refreshed via query invalidation when
+ * lore-data-changed events are received.
+ */
+
+import { useQuery } from "@tanstack/react-query";
+import { getLoreStatus } from "@/lib/tauri";
+import type { LoreStatus } from "@/lib/bindings";
+
+export interface UseLoreDataResult {
+  data: LoreStatus | undefined;
+  isLoading: boolean;
+  error: Error | null;
+  refetch: () => void;
+}
+
+/**
+ * Fetch lore status data from the Tauri backend.
+ *
+ * Returns the current lore status including health, last sync time,
+ * and summary counts (open issues, authored MRs, reviewing MRs).
+ */
+export function useLoreData(): UseLoreDataResult {
+  const query = useQuery({
+    queryKey: ["lore-status"],
+    queryFn: async (): Promise<LoreStatus> => {
+      const result = await getLoreStatus();
+
+      if (result.status === "error") {
+        throw new Error(result.error.message);
+      }
+
+      return result.data;
+    },
+    refetchInterval: false, // Manual refetch on lore-data-changed
+    staleTime: 30_000, // Consider data fresh for 30 seconds
+  });
+
+  return {
+    data: query.data,
+    isLoading: query.isLoading,
+    error: query.error,
+    refetch: query.refetch,
+  };
+}