fix(search): prevent autocomplete dropdown opening on mount

Add user interaction tracking to SearchInput component to prevent
the autocomplete dropdown from automatically opening when the component
mounts with query parameters in the URL. The dropdown now only opens
after the user has interacted with the input field (typing or focusing).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ericyangpan

src/components/controls/SearchInput.tsx

@@ -26,6 +26,7 @@ export default function SearchInput({
   const inputRef = useRef<HTMLInputElement>(null)
   const dropdownRef = useRef<HTMLDivElement>(null)
   const debounceTimerRef = useRef<NodeJS.Timeout | null>(null)
+  const hasUserInteracted = useRef(false)
 
   const placeholderText = placeholder || t('components.header.searchPlaceholder')
 
@@ -39,7 +40,10 @@ export default function SearchInput({
       debounceTimerRef.current = setTimeout(() => {
         const results = getAutocompleteSuggestions(query)
         setSuggestions(results)
-        setIsOpen(results.length > 0)
+        // Only auto-open dropdown if user has interacted with the input
+        if (hasUserInteracted.current && results.length > 0) {
+          setIsOpen(true)
+        }
         setSelectedIndex(-1)
       }, 300)
     } else {
@@ -74,6 +78,8 @@ export default function SearchInput({
 
   const handleInputChange = (value: string) => {
     setQuery(value)
+    // Mark as user interaction to allow dropdown to open
+    hasUserInteracted.current = true
   }
 
   const handleSearch = (searchQuery: string) => {
@@ -120,6 +126,12 @@ export default function SearchInput({
           value={query}
           onChange={e => handleInputChange(e.target.value)}
           onKeyDown={handleKeyDown}
+          onFocus={() => {
+            hasUserInteracted.current = true
+            if (query.trim() && suggestions.length > 0) {
+              setIsOpen(true)
+            }
+          }}
           placeholder={placeholderText}
           className="w-full px-[var(--spacing-sm)] py-1 text-sm border border-[var(--color-border)] bg-[var(--color-background)] text-[var(--color-text)] placeholder:text-[var(--color-text-muted)] focus:outline-none focus:border-[var(--color-border-strong)] transition-colors"
         />