One-tap discard from the hand: select a card, 'Discard it'

Shedding a single card meant entering discard mode, marking, and
confirming. Now any selected card offers 'Discard it' right in its
action strip — beside 'Drop it here' when the card is an object, so
the drop-or-discard choice sits in one place. The bulk discard flow
stays for multi-card sheds.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0138A8CjeQRpvzKxuMfz1Bqc

packages/web/src/App.svelte

@@ -1884,6 +1884,12 @@
                 clearSelection();
               }}>Drop it here</button>
             {/if}
+            {#if selectedCard && isYourTurn && !youMustRespond}
+              <button class="stamp tiny discard-one" onclick={() => {
+                if (selectedCard) dispatch({ type: "discard", instanceIds: [selectedCard.instanceId] });
+                clearSelection();
+              }}>Discard it</button>
+            {/if}
             {#if selectedCard?.cardId === "add"}
               <span>— ADD rides a second NUMBER: play one number for movement,
                 then play another, and the Add spends itself</span>
@@ -2347,6 +2353,7 @@
   .stamp.primary:hover:not(:disabled) { background: #5a4429; }
   .stamp.big { font-size: 0.95rem; padding: 0.6rem 1.3rem; }
   .stamp.tiny { font-size: 0.62rem; padding: 0.22rem 0.5rem; box-shadow: 1px 1px 0 rgba(0,0,0,0.3); }
+  .stamp.discard-one { background: #8a7a5e; }
   .stamp:focus-visible { outline: 2px solid #d8b23a; outline-offset: 2px; }
 
   .game {