style(ui): match game-folder topbar design

Follow the latest top-bar spec for the Game Folder control. The button stays
as only the folder icon and short label, with the full path in tooltip and aria
text, and now sits in the app-level control group with the kebab menu on the
far-right edge of the wide top bar.

This keeps Sort as the right-zone lead control next to the centered search
cluster while treating Game Folder and the kebab menu as a tight trailing pair.
The narrow fallback still flows in source order: sort, game folder, kebab.

Test Plan:
- git diff --check
- rg -n "dirbtn-status-dot|status dot|green status|red status" crates/lanspread-tauri-deno-ts/src
- just frontend-test
- just build

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

@@ -23,7 +23,6 @@ export const DirectoryButton = ({ path, exists, onClick }: Props) => {
         >
             <Icon.folder />
             <span className="dirbtn-label">{label}</span>
-            <span className="dirbtn-status-dot" aria-hidden="true" />
         </button>
     );
 };

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

@@ -51,8 +51,10 @@ export const TopBar = ({
             <div className="topbar-right-lead">
                 <SortMenu value={sort} onChange={setSort} />
             </div>
-            <DirectoryButton path={gameDir} exists={gameDirExists} onClick={onPickDirectory} />
-            <KebabMenu items={kebabItems} />
+            <div className="topbar-right-tail">
+                <DirectoryButton path={gameDir} exists={gameDirExists} onClick={onPickDirectory} />
+                <KebabMenu items={kebabItems} />
+            </div>
         </div>
     </header>
 );