feat(ui): move game folder picker into settings

The design update moved game-folder configuration out of launcher chrome and
into Settings > Library. Follow that contract in the runtime UI without
changing the existing storage or Tauri directory commands.

The top bar now leaves its right edge for the kebab menu. Settings owns a new
Game folder row that shows a valid selected path with a neutral Change button,
or the red Not set state with a stronger Choose button when no accessible
directory is configured. Both the empty-library state and the Settings row
still use the existing native directory picker, so existing saved paths and
rescans keep their current behavior.

Keep useGameDirectory as the directory-state owner and expose the shared
hasGameDirectory boolean from that hook so the grid and Settings field agree on
what counts as configured.

Test Plan:
- git diff --cached --check
- just frontend-test
- just build

Refs: 62b409f4bfc4995c25461776107d28f52b24f30e

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

@@ -1,28 +0,0 @@
-import { Icon } from '../Icon';
-
-interface Props {
-    path: string | null;
-    exists: boolean;
-    onClick: () => void;
-}
-
-export const DirectoryButton = ({ path, exists, onClick }: Props) => {
-    const isSet = !!(path && path.trim());
-    const isValid = isSet && exists;
-    const label = isValid ? 'Game folder' : 'Set game folder';
-    const tooltip = isValid ? (path as string) : 'Please select a game folder';
-    const ariaLabel = isValid ? `Game folder: ${path}` : 'Set game folder';
-
-    return (
-        <button
-            type="button"
-            className={`dirbtn ${isValid ? 'dirbtn-set' : 'dirbtn-unset'}`}
-            title={tooltip}
-            aria-label={ariaLabel}
-            onClick={onClick}
-        >
-            <Icon.folder />
-            <span className="dirbtn-label">{label}</span>
-        </button>
-    );
-};

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

@@ -2,7 +2,6 @@ import { Brand } from '../Brand';
 import { SegmentedFilters } from './SegmentedFilters';
 import { SearchField } from './SearchField';
 import { SortMenu } from './SortMenu';
-import { DirectoryButton } from './DirectoryButton';
 import { KebabMenu, KebabItem } from './KebabMenu';
 
 import { FilterCounts } from '../../lib/gameState';
@@ -17,9 +16,6 @@ interface Props {
     setQuery: (value: string) => void;
     sort: GameSort;
     setSort: (value: GameSort) => void;
-    gameDir: string;
-    gameDirExists: boolean;
-    onPickDirectory: () => void;
     kebabItems: ReadonlyArray<KebabItem>;
 }
 
@@ -32,9 +28,6 @@ export const TopBar = ({
     setQuery,
     sort,
     setSort,
-    gameDir,
-    gameDirExists,
-    onPickDirectory,
     kebabItems,
 }: Props) => (
     <header className="topbar">
@@ -52,7 +45,6 @@ export const TopBar = ({
                 <SortMenu value={sort} onChange={setSort} />
             </div>
             <div className="topbar-right-tail">
-                <DirectoryButton path={gameDir} exists={gameDirExists} onClick={onPickDirectory} />
                 <KebabMenu items={kebabItems} />
             </div>
         </div>