Stage 17 #5: make the active-row chevron open the game (not a no-op)

Owner review: the '>' on an active game row should be a real tap target that opens
the game, like the rest of the row — not inert. The chevron now navigates (kept out
of the tab order / a11y tree since the row's main button already does the same), and
active-row swipes no longer suppress the tap. Adds an e2e for the chevron navigation.

ui/src/screens/Lobby.svelte

@@ -79,9 +79,11 @@
     if (!drag) return;
     const dx = e.clientX - drag.x0;
     const dy = e.clientY - drag.y0;
-    if (Math.abs(dx) > 40 && Math.abs(dx) > Math.abs(dy) * 1.4) {
+    // Only a finished row reveals on a horizontal swipe; that swipe then suppresses the tap so it
+    // does not also open the game. Active rows ignore swipes and stay plain tap-to-open.
+    if (finished && Math.abs(dx) > 40 && Math.abs(dx) > Math.abs(dy) * 1.4) {
       swiped = true;
-      revealedId = dx < 0 && finished ? drag.id : null;
+      revealedId = dx < 0 ? drag.id : null;
     }
     drag = null;
   }
@@ -207,7 +209,9 @@
                   {#if group.finished}
                     <button class="kebab" onclick={() => toggleReveal(g.id)} aria-label={t('lobby.hideGame')}>⋮</button>
                   {:else}
-                    <span class="chev" aria-hidden="true">›</span>
+                    <!-- A visual duplicate of the row's tap target: opens the game on tap, but kept out
+                         of the tab order / a11y tree since the .open button already does the same. -->
+                    <button class="chev" onclick={() => openGame(g)} tabindex={-1} aria-hidden="true">›</button>
                   {/if}
                 </div>
               </div>
@@ -341,6 +345,9 @@
   .chev {
     flex: 0 0 auto;
     width: 30px;
+    padding: 10px 0;
+    border: none;
+    background: none;
     text-align: center;
     color: var(--text-muted);
     font-size: 1.4rem;