fix(ui): handle enter and escape in search

The search field should behave like a transient launcher search control. Enter
now blurs the input while preserving the current term, and Escape clears the
term before blurring the input.

Test Plan:
- git diff --check

Refs: user redesign nitpick about search keyboard behavior

crates/lanspread-tauri-deno-ts/src/components/topbar/SearchField.tsx

@@ -26,6 +26,8 @@ export const SearchField = ({ value, onChange }: Props) => {
         return () => window.removeEventListener('keydown', onKey);
     }, []);
 
+    const blurInput = () => inputRef.current?.blur();
+
     return (
         <div className="search">
             <Icon.search />
@@ -35,6 +37,16 @@ export const SearchField = ({ value, onChange }: Props) => {
                 placeholder="Search games"
                 value={value}
                 onChange={(e) => onChange(e.target.value)}
+                onKeyDown={(e) => {
+                    if (e.key === 'Enter') {
+                        e.preventDefault();
+                        blurInput();
+                    } else if (e.key === 'Escape') {
+                        e.preventDefault();
+                        onChange('');
+                        blurInput();
+                    }
+                }}
                 spellCheck={false}
             />
             <span className="search-kbd">/</span>