feat: convert all human fights to multiple choice, remove text input

Creative challenges (roast_battle, creative_writing, meme_war,
code_golf, wrestling_match) now auto-generate multiple choice options
from per-type response pools: 1 good answer + 3 weaker distractors.
The free text input UI is commented out but preserved for future use.

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

server/src/engine/human-responses.ts

@@ -157,7 +157,7 @@ const CREATIVE_POOLS: Record<string, { good: string[]; medium: string[]; bad: st
     ],
     bad: [
       "print('hello world')",
-      "pass # TODO: implement",
+      "x=input();print(len(x))",
       "x = 42  # the answer",
       "return True  # ship it",
       "// no idea what to write",
@@ -200,8 +200,8 @@ function generateChoices(challenge: Challenge): string[] {
     // Text answer — pick distractors from same challenge type
     const pool = getAnswerPool(challenge.type)
     const correctLower = challenge.answers.map(a => a.toLowerCase())
-    const candidates = pool.filter(a => !correctLower.includes(a.toLowerCase()))
-    shuffle(candidates)
+    let candidates = pool.filter(a => !correctLower.includes(a.toLowerCase()))
+    candidates = shuffle(candidates)
 
     if (candidates.length >= 2) {
       return shuffle([correct, candidates[0], candidates[1]])
@@ -314,3 +314,10 @@ export function getPendingChallenge(
     choices: entry.choices,
   }
 }
+
+/** Get the accepted answers for a pending challenge (for correctness feedback) */
+export function getPendingAnswers(fightId: string, botId: string): string[] | undefined {
+  const key = `${fightId}:${botId}`
+  const entry = pending.get(key)
+  return entry?.challenge.answers
+}