feat(web): add React Query, dark mode toggle, and error retry UX

- Install @tanstack/react-query with exponential backoff retry config
- Create QueryClientProvider and custom hooks for listings, analytics,
  payments, and subscription API calls
- Migrate 5 dashboard pages from useState/useEffect to React Query hooks
- Add dark mode CSS variables and ThemeProvider with localStorage persistence
- Add theme toggle button in dashboard header (sun/moon icon)
- Enhance error boundaries with auto-retry, retry count, and loading state

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/app/(public)/search/error.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useEffect } from 'react';
+import { useEffect, useState } from 'react';
 
 export default function SearchError({
   error,
@@ -9,10 +9,29 @@ export default function SearchError({
   error: Error & { digest?: string };
   reset: () => void;
 }) {
+  const [retryCount, setRetryCount] = useState(0);
+  const [autoRetrying, setAutoRetrying] = useState(false);
+
   useEffect(() => {
     console.error('Search error:', error);
   }, [error]);
 
+  useEffect(() => {
+    if (retryCount > 0) return;
+    setAutoRetrying(true);
+    const timer = setTimeout(() => {
+      setAutoRetrying(false);
+      setRetryCount((c) => c + 1);
+      reset();
+    }, 3000);
+    return () => clearTimeout(timer);
+  }, [error, reset, retryCount]);
+
+  const handleRetry = () => {
+    setRetryCount((c) => c + 1);
+    reset();
+  };
+
   return (
     <div className="mx-auto max-w-7xl px-4 py-6">
       <div className="flex min-h-[400px] flex-col items-center justify-center">
@@ -34,17 +53,35 @@ export default function SearchError({
           </div>
           <h2 className="mt-4 text-xl font-semibold">Lỗi tìm kiếm</h2>
           <p className="mt-2 text-sm text-muted-foreground">
-            Không thể thực hiện tìm kiếm. Vui lòng thử lại hoặc thay đổi bộ lọc.
+            {autoRetrying
+              ? 'Đang tự động thử lại...'
+              : 'Không thể thực hiện tìm kiếm. Vui lòng thử lại hoặc thay đổi bộ lọc.'}
           </p>
           {error.digest && (
             <p className="mt-1 text-xs text-muted-foreground">Mã lỗi: {error.digest}</p>
           )}
+          {retryCount > 0 && (
+            <p className="mt-1 text-xs text-muted-foreground">
+              Đã thử lại {retryCount} lần
+            </p>
+          )}
           <div className="mt-6 flex justify-center gap-3">
             <button
-              onClick={reset}
-              className="inline-flex h-9 items-center rounded-md bg-primary px-4 text-sm font-medium text-primary-foreground shadow transition-colors hover:bg-primary/90"
+              onClick={handleRetry}
+              disabled={autoRetrying}
+              className="inline-flex h-9 items-center rounded-md bg-primary px-4 text-sm font-medium text-primary-foreground shadow transition-colors hover:bg-primary/90 disabled:opacity-50"
             >
-              Thử lại
+              {autoRetrying ? (
+                <>
+                  <svg className="mr-2 h-4 w-4 animate-spin" viewBox="0 0 24 24" fill="none">
+                    <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
+                    <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z" />
+                  </svg>
+                  Đang thử lại...
+                </>
+              ) : (
+                'Thử lại'
+              )}
             </button>
             <a
               href="/"