feat: human vs AI mode — live typing challenges, baby growth system, SSE rounds

- Add choose-mode step: "I BUILD BOTS" vs "I FIGHT MYSELF" paths
- Human registration with baby avatar picker, no webhook required
- Live fight scene with SSE round streaming and real-time challenge UI
- 5-second timer per round, submit answers via browser
- Baby → toddler → kid → teen → adult → hero → super growth stages
- Huge sparkly baby eyes, diapers, pacifiers, bibs, rattles, rosy cheeks
- Speech bubble positioning fix (pushed to outside of sprite)
- Canvas text rendering via offscreen canvas to bypass kaplay color issues
- Voice timing improvements: await pauses between voice lines and hits
- 30 devastating announcement lines, 15 critical/hit word variants
- Orchestrator human player detection + waitForHumanResponse system
- Server endpoints: GET /challenge/:botId, POST /respond/:botId
- Human player auth: register-human route, isHuman flag on login

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/BotProfilePage.vue

@@ -279,9 +279,21 @@ const tierClass = (t: number) => `tier-${t}`
       </div>
 
       <template v-else>
-        <!-- Header with human + bot character -->
+        <!-- Header -->
         <div class="text-center mb-5">
-          <div class="flex items-end justify-between mb-3 relative">
+          <!-- Human player: just the human avatar, centered -->
+          <div v-if="stats.archetype === 'human'" class="flex justify-center mb-3">
+            <HumanPreview
+              :seed="stats.avatarSeed || stats.name"
+              archetype="human"
+              :size="220"
+              :win-rate="(stats.winRate || 0) / 100"
+              anim="idle"
+              class="drop-shadow-[0_0_20px_rgba(0,255,255,0.3)]"
+            />
+          </div>
+          <!-- Bot player: human controller + wire + bot sprite -->
+          <div v-else class="flex items-end justify-between mb-3 relative">
             <HumanPreview
               :seed="stats.avatarSeed || stats.name"
               :archetype="stats.archetype || 'standard'"
@@ -338,7 +350,7 @@ const tierClass = (t: number) => `tier-${t}`
             #{{ stats.rank }} of {{ stats.totalBots }}
           </p>
           <button
-            v-if="isOwner"
+            v-if="isOwner && stats.archetype !== 'human'"
             class="mt-2 font-mono text-[10px] text-neon-cyan/60 hover:text-neon-cyan transition-colors"
             @click="showCustomize = !showCustomize; if (showCustomize) initCustForm()"
           >