fix(social): robot blocks

Blocking an auto-match opponent who is secretly a pooled robot is recorded  instead in a separate `robot_blocks` table.

Now blocking behaves the same in that game (struck name, hidden composer) and lists the blocked opponent under the name you saw, but is recorded only against that game — the disguise holds, the shared robot is never globally blocked, and the matchmaker keeps pairing you with robots (so you can never block yourself out of opponents).

- the shared robot account is never put in `blocks`
- the matchmaker keeps it free and it is not blocked under its other per-game names
- the blocked list and the in-game card still show it by joining that table; an unblock deletes the row

ui/src/screens/Friends.svelte

@@ -8,21 +8,27 @@
   import { translate } from '../lib/i18n/catalog';
   import { friendCodeParam, shareLink } from '../lib/deeplink';
   import { shareTelegramLink } from '../lib/telegram';
-  import type { AccountRef, FriendCode } from '../lib/model';
+  import type { AccountRef, FriendCode, RobotBlockEntry } from '../lib/model';
 
   let friends = $state<AccountRef[]>([]);
   let incoming = $state<AccountRef[]>([]);
   let blocked = $state<AccountRef[]>([]);
+  // Per-game disguised-robot blocks, shown as distinct entries alongside blocked humans.
+  let robotBlocks = $state<RobotBlockEntry[]>([]);
   let code = $state<FriendCode | null>(null);
   let redeemInput = $state('');
 
   async function load() {
     try {
-      [friends, incoming, blocked] = await Promise.all([
+      const [fl, inc, bl] = await Promise.all([
         gateway.friendsList(),
         gateway.friendsIncoming(),
         gateway.blocksList(),
       ]);
+      friends = fl;
+      incoming = inc;
+      blocked = bl.blocked;
+      robotBlocks = bl.robots;
     } catch (e) {
       handleError(e);
     }
@@ -179,7 +185,7 @@
       {/if}
     </section>
 
-    {#if blocked.length}
+    {#if blocked.length || robotBlocks.length}
       <section>
         <h3>{t('friends.blockedList')}</h3>
         {#each blocked as b (b.accountId)}
@@ -188,6 +194,12 @@
             <button class="ghost" onclick={() => unblock(b.accountId)} disabled={!connection.online}>{t('friends.unblock')}</button>
           </div>
         {/each}
+        {#each robotBlocks as r (r.id)}
+          <div class="item">
+            <span class="who">{r.displayName}</span>
+            <button class="ghost" onclick={() => unblock(r.id)} disabled={!connection.online}>{t('friends.unblock')}</button>
+          </div>
+        {/each}
       </section>
     {/if}
   {/if}