Mega-Monster offers its choice

"Doubles the existing life-points OR movement rate" — the engine
always took the OR's left side because the client never asked. With
Mega-Monster selected, the hint bar now offers the choice (hit points
lit by default), and the pick rides the cast as params.boost — its
own field, freeing params.cardId for the name-a-card spells it
belongs to. Both halves of the OR are pinned in the creature suite.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

packages/web/src/App.svelte

@@ -88,6 +88,8 @@
   let tradeFrom = $state<{ x: number; y: number } | null>(null);
   /** rotate-sector direction. */
   let rotateCW = $state(true);
+  /** mega-monster: which stat the chosen monster doubles. */
+  let megaBoost = $state<"life" | "movement">("life");
   /** Cards marked for discard. */
   let discardSelection = $state<Set<string>>(new Set());
   /** Voluntary discard mode: hand clicks mark cards instead of playing them. */
@@ -226,6 +228,7 @@
     tradeFrom = null;
     selectedCreature = null;
     selectedCard = null;
+    megaBoost = "life";
     attachedNumber = null;
     attachedMods = [];
     wbDamage = 0;
@@ -614,6 +617,7 @@
       dispatch({
         type: "cast", instanceId: selectedCard.instanceId,
         target: { kind: "creature", creatureId },
+        ...(selectedCard.cardId === "mega-monster" ? { params: { boost: megaBoost } } : {}),
         ...(attachedNumber ? { numberInstanceIds: [attachedNumber.instanceId] } : {}),
       });
       clearSelection();
@@ -1378,6 +1382,14 @@
             {:else if selectedCard && TWO_CELL_CARDS.has(selectedCard.cardId)}
               <span>{tradeFrom ? "— now the second square" : "— click the first square"}</span>
             {/if}
+            {#if selectedCard?.cardId === "mega-monster"}
+              <span>— double its</span>
+              <button class="stamp tiny" class:lit={megaBoost === "life"}
+                onclick={() => (megaBoost = "life")}>hit points</button>
+              <button class="stamp tiny" class:lit={megaBoost === "movement"}
+                onclick={() => (megaBoost = "movement")}>movement</button>
+              <span>— then tap the monster</span>
+            {/if}
             {#if selectedCard?.cardId === "rotate-sector"}
               <label class="inline"><input type="checkbox" bind:checked={rotateCW} /> clockwise</label>
               <span>— click the sector</span>
@@ -1857,6 +1869,10 @@
     cursor: pointer;
     box-shadow: 2px 2px 0 rgba(0, 0, 0, 0.35);
   }
+  .stamp.lit {
+    background: #43331f;
+    color: #e9e1cb;
+  }
   .stamp:hover:not(:disabled) { background: #f4eede; }
   .stamp:active:not(:disabled) { transform: translate(1px, 1px); box-shadow: 1px 1px 0 rgba(0,0,0,0.35); }
   .stamp:disabled { opacity: 0.45; cursor: default; }