feat(offline): hotseat lobby delete behind the master PIN

Lobby.svelte: hotseat games show the kebab / swipe delete in BOTH the
active and finished groups (not finished-only); deleting one opens a
master-PIN pad first — active = terminate (no result), finished = remove
— so the last mover cannot instantly wipe a game. Local games stay
deletable offline. Non-hotseat games are unchanged (finished-only, free).

ui/src/screens/Lobby.svelte

@@ -4,6 +4,7 @@
   import Screen from '../components/Screen.svelte';
   import TabBar from '../components/TabBar.svelte';
   import Modal from '../components/Modal.svelte';
+  import PinPad from '../components/PinPad.svelte';
   import { app, handleError, refreshFeedbackBadge, seedChatUnread } from '../lib/app.svelte';
   import { connection } from '../lib/connection.svelte';
   import { gateway } from '../lib/gateway';
@@ -186,6 +187,9 @@
   // revealed by swiping the row left (touch) or tapping its kebab (any pointer); the action is
   // per-account and irreversible. Only one row is revealed at a time.
   let revealedId = $state<string | null>(null);
+  // A hotseat game's deletion is gated by the host (master) PIN — both active (terminate the game)
+  // and finished; pinTarget holds the game id while its PIN pad is open.
+  let pinTarget = $state<string | null>(null);
   let drag: { id: string; x0: number; y0: number } | null = null;
   // A horizontal swipe must not also count as a tap that opens the game; armed on swipe,
   // consumed by the next tap, and reset on the next pointerdown so a later tap is never eaten.
@@ -196,13 +200,14 @@
     if (e.pointerType === 'mouse') return; // desktop reveals via the kebab, not a swipe
     drag = { id, x0: e.clientX, y0: e.clientY };
   }
-  function onRowUp(e: PointerEvent, finished: boolean): void {
+  function onRowUp(e: PointerEvent, revealable: boolean): void {
     if (!drag) return;
     const dx = e.clientX - drag.x0;
     const dy = e.clientY - drag.y0;
-    // 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) {
+    // Only a revealable row (a finished game, or any hotseat game) reveals its delete on a horizontal
+    // swipe; that swipe then suppresses the tap so it does not also open the game. Other active rows
+    // ignore swipes and stay plain tap-to-open.
+    if (revealable && Math.abs(dx) > 40 && Math.abs(dx) > Math.abs(dy) * 1.4) {
       swiped = true;
       revealedId = dx < 0 ? drag.id : null;
     }
@@ -240,6 +245,14 @@
     }
   }
 
+  // startDelete routes the row's delete: a hotseat game (active or finished) is gated behind the host
+  // master PIN (so the last mover cannot instantly wipe the game); any other finished game deletes at
+  // once.
+  function startDelete(g: GameView): void {
+    if (g.hotseat) pinTarget = g.id;
+    else void hide(g.id);
+  }
+
   async function acceptInvite(inv: Invitation) {
     try {
       const r = await gateway.invitationAccept(inv.id);
@@ -315,15 +328,15 @@
           <div class="list">
             {#each group.list as g (g.id)}
               {@const badge = badgeKind(app.chatUnread[g.id] ?? false, app.messageUnread[g.id] ?? false)}
-              <div class="rowwrap" class:revealed={group.finished && revealedId === g.id}>
-                {#if group.finished}
-                  <button class="del" onclick={() => hide(g.id)} disabled={!connection.online} aria-label={t('lobby.hideGame')}>❌</button>
+              <div class="rowwrap" class:revealed={(group.finished || g.hotseat) && revealedId === g.id}>
+                {#if group.finished || g.hotseat}
+                  <button class="del" onclick={() => startDelete(g)} disabled={!isLocalGameId(g.id) && !connection.online} aria-label={t('lobby.hideGame')}>❌</button>
                 {/if}
                 <div class="row">
                   <button
                     class="open"
                     onpointerdown={(e) => onRowDown(e, g.id)}
-                    onpointerup={(e) => onRowUp(e, group.finished)}
+                    onpointerup={(e) => onRowUp(e, group.finished || !!g.hotseat)}
                     onclick={() => openGame(g)}
                   >
                     <span class="info">
@@ -345,7 +358,7 @@
                       <span class="emoji" class:blink={blinkingIds.has(g.id)}>{resultBadge(g, myId).emoji}</span>
                     {/key}
                   </button>
-                  {#if group.finished}
+                  {#if group.finished || g.hotseat}
                     <button class="kebab" onclick={() => toggleReveal(g.id)} aria-label={t('lobby.hideGame')}>⋮</button>
                   {:else}
                     <!-- A visual duplicate of the row's tap target: opens the game on tap, but kept out
@@ -378,6 +391,21 @@
     </Modal>
   {/if}
 
+  <!-- Deleting a hotseat game (active or finished) is gated by the host master PIN. -->
+  {#if pinTarget}
+    <PinPad
+      mode="verify"
+      title={t('hotseat.hostPin')}
+      verify={(p) => localSource.verifyHostPin(pinTarget ?? '', p)}
+      onclose={() => (pinTarget = null)}
+      onresult={() => {
+        const id = pinTarget;
+        pinTarget = null;
+        if (id) void hide(id);
+      }}
+    />
+  {/if}
+
   {#snippet tabbar()}
     <TabBar>
       <button class="tab" disabled={atGameLimit} onclick={() => navigate('/new')}>