fix: interpret Choice.timeLimit as seconds, convert to ms internally

Previously maxLimit was passed directly to setTimeout/setInterval (ms),
so a JSON value of 10 meant 10ms instead of the intended 10 seconds.
Now timeLimit in JSON represents seconds, engine multiplies by 1000.

engine/systems/ChoiceSystem.ts

@@ -23,11 +23,10 @@ export class ChoiceSystem {
     const timed = choices.filter((c) => c.timeLimit && c.timeLimit > 0)
     if (timed.length === 0) return
 
-    const maxLimit = Math.max(...timed.map((c) => c.timeLimit!))
+    const maxLimitSec = Math.max(...timed.map((c) => c.timeLimit!))
+    const maxLimitMs = maxLimitSec * 1000
 
-    const maxLimitSec = maxLimit / 1000
-
-    this.timeLimit = maxLimit
+    this.timeLimit = maxLimitMs
     this.elapsed = 0
     this.onUpdate = onUpdate
     this.onTimeout = onTimeout
@@ -36,21 +35,19 @@ export class ChoiceSystem {
 
     this.timerId = setInterval(() => {
       this.elapsed += this.tickMs
-      const remaining = Math.max(0, this.timeLimit - this.elapsed) / 1000
-      const nextState: ChoiceTimerState = {
-        total: this.timeLimit / 1000,
-        remaining: Math.ceil(remaining * 10) / 10,
-      }
-      this.onUpdate?.(nextState)
+      const remainingSec = Math.max(0, maxLimitMs - this.elapsed) / 1000
+      this.onUpdate?.({
+        total: maxLimitSec,
+        remaining: Math.ceil(remainingSec * 10) / 10,
+      })
     }, this.tickMs)
 
     this.timeoutId = setTimeout(() => {
       this.clear()
-      // Pick the first choice as default on timeout
       if (choices.length > 0) {
         this.onTimeout?.(choices[0])
       }
-    }, this.timeLimit)
+    }, maxLimitMs)
   }
 
   stop() {