feat: Add UX optimizations - skeletons and optimistic hooks

- Add Skeletons.tsx with TastingListSkeleton, ChartSkeleton, etc.
- Add useOptimistic.ts hooks for React 19 optimistic updates
- Update stats page to use skeleton loading instead of spinner
- Remove force-dynamic exports (12 files) for SSG compatibility
- Note: PPR (cacheComponents) tested but reverted - requires RSC-first refactor

src/hooks/useOptimistic.ts

@@ -0,0 +1,70 @@
+'use client';
+
+import { useOptimistic, useTransition } from 'react';
+
+/**
+ * Hook for optimistic updates with automatic rollback on error.
+ * Uses React 19's useOptimistic + startTransition pattern.
+ * 
+ * @example
+ * const { optimisticData, isPending, mutate } = useOptimisticMutation(
+ *   tastings,
+ *   async (newTasting) => await saveTasting(newTasting)
+ * );
+ */
+export function useOptimisticMutation<T, TInput>(
+    initialData: T[],
+    mutationFn: (input: TInput) => Promise<{ success: boolean; error?: string }>
+) {
+    const [isPending, startTransition] = useTransition();
+
+    const [optimisticData, addOptimistic] = useOptimistic<T[], TInput>(
+        initialData,
+        (currentData, newItem) => [...currentData, newItem as unknown as T]
+    );
+
+    const mutate = async (input: TInput, optimisticValue: T) => {
+        startTransition(async () => {
+            // Immediately show optimistic update
+            addOptimistic(input);
+
+            // Perform actual mutation
+            const result = await mutationFn(input);
+
+            if (!result.success) {
+                console.error('[OptimisticMutation] Failed:', result.error);
+                // Note: React will automatically rollback on error
+            }
+        });
+    };
+
+    return {
+        optimisticData,
+        isPending,
+        mutate,
+    };
+}
+
+/**
+ * Simple optimistic state for single values (like ratings).
+ */
+export function useOptimisticValue<T>(
+    serverValue: T,
+    updateFn: (value: T) => Promise<{ success: boolean }>
+) {
+    const [isPending, startTransition] = useTransition();
+    const [optimisticValue, setOptimistic] = useOptimistic(serverValue);
+
+    const setValue = (value: T) => {
+        startTransition(async () => {
+            setOptimistic(value);
+            await updateFn(value);
+        });
+    };
+
+    return {
+        value: optimisticValue,
+        isPending,
+        setValue,
+    };
+}