The mystery machine keeps its mood to itself

"Random" read as random ACTIONS, and a revealed random pick is barely
a mystery anyway. The fourth workshop button is now "mystery": the
server rolls the temperament and keeps it — the join line records it
for replay, the drive loop plays it, but the room tells the table
only "mystery". Roster and scoresheet show ⚙ mystery; the machine's
behavior is the only tell.

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

packages/web/src/App.svelte

@@ -1055,7 +1055,7 @@
               <button class="stamp tiny" onclick={() => net.addBot("hunter")}>hunter</button>
               <button class="stamp tiny" onclick={() => net.addBot("berserker")}>berserker</button>
               <button class="stamp tiny" onclick={() => net.addBot("worrier")}>worrier</button>
-              <button class="stamp tiny" onclick={() => net.addBot()}>random</button>
+              <button class="stamp tiny" onclick={() => net.addBot()}>mystery</button>
             </span>
           {/if}
           <label class="check">