refactor: simplify LoadingErrorState and enhance MarketSearchBar functionality

- Removed unnecessary imports and streamlined the LoadingErrorState component by eliminating redundant props.
- Improved keyboard handling in MarketSearchBar to support basic Escape key functionality and enhanced keyboard shortcuts.
- Updated MerchantStore and MarketPage components to utilize the revised LoadingErrorState and MarketSearchBar, ensuring consistent loading/error handling and search capabilities.
- Enhanced StallView to provide better category filtering and product search experience.

These changes improve code clarity and maintainability while enhancing user interaction across the market module.

src/modules/market/components/MarketSearchBar.vue

@@ -292,14 +292,26 @@ const handleClear = () => {
 }
 
 const handleKeydown = (event: KeyboardEvent) => {
-  if (!props.showEnhancements || !useSearchKeyboardShortcuts.value) return
+  if (!props.showEnhancements) return
 
-  const shouldClear = handleSearchKeydown(event)
-  if (shouldClear) {
+  // Handle basic Escape key for simple mode
+  if (event.key === 'Escape') {
+    event.preventDefault()
     if (searchQuery.value) {
       handleClear()
-    } else {
-      blurSearchInput()
+    }
+    return
+  }
+
+  // Use enhanced keyboard shortcuts if available
+  if (useSearchKeyboardShortcuts.value && handleSearchKeydown) {
+    const shouldClear = handleSearchKeydown(event)
+    if (shouldClear) {
+      if (searchQuery.value) {
+        handleClear()
+      } else {
+        blurSearchInput()
+      }
     }
   }
 }
@@ -347,7 +359,7 @@ const handleBlur = () => {
 // Enhanced mode methods (initialized conditionally)
 let focusSearchInput = () => {}
 let blurSearchInput = () => {}
-let handleSearchKeydown = () => false
+let handleSearchKeydown = (_event: KeyboardEvent) => false
 
 // Initialize keyboard shortcuts for enhanced mode
 watch(() => props.showEnhancements, async (showEnhancements) => {