feat(遊戲化): 新增大廳、附身、時間流、後日談進度等遊戲化系統功能

新增角色大廳（lobby）邀約與通話、附身（possession）、時鐘（clock）抽象、
時間流與睡眠負債、後日談進度、行為選擇與旁觀反應等模組，並補齊對應冒煙
測試（R~V）與單元測試；同步調整 web/mobile 對應頁面與元件。

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

apps/mobile/components/HeartbeatDot.tsx

@@ -0,0 +1,42 @@
+import { useEffect, useRef } from "react";
+import { Animated, Easing, type StyleProp, type ViewStyle } from "react-native";
+import { useReduceMotion } from "../lib/reduce-motion";
+
+export interface HeartbeatDotProps {
+  size?: number;
+  color?: string;
+  style?: StyleProp<ViewStyle>;
+}
+
+// Q-4：未讀／推播提示紅點＝小心跳，對應 apps/web 的 `.heartbeat-dot`（1.2s 循環的 opacity+scale 脈動）。
+export function HeartbeatDot({ size = 10, color = "#FF7E9D", style }: HeartbeatDotProps) {
+  const reduceMotion = useReduceMotion();
+  const t = useRef(new Animated.Value(0)).current;
+
+  useEffect(() => {
+    if (reduceMotion) {
+      t.setValue(0);
+      return;
+    }
+    const loop = Animated.loop(
+      Animated.sequence([
+        Animated.timing(t, { toValue: 1, duration: 600, easing: Easing.inOut(Easing.ease), useNativeDriver: true }),
+        Animated.timing(t, { toValue: 0, duration: 600, easing: Easing.inOut(Easing.ease), useNativeDriver: true }),
+      ]),
+    );
+    loop.start();
+    return () => loop.stop();
+  }, [reduceMotion, t]);
+
+  const scale = t.interpolate({ inputRange: [0, 1], outputRange: [1, 1.3] });
+  const opacity = t.interpolate({ inputRange: [0, 1], outputRange: [1, 0.7] });
+
+  return (
+    <Animated.View
+      style={[
+        { width: size, height: size, borderRadius: size / 2, backgroundColor: color, opacity, transform: [{ scale }] },
+        style,
+      ]}
+    />
+  );
+}