功能：实现 Group_Horse_Racing 群赛马插件

- 新增群赛马游戏插件，支持多人参与赛马竞猜

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

danding_bot/plugins/group_horse_racing/race_engine.py

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+import asyncio
+import random
+from typing import Optional
+
+from .models import Room, RoomState, Horse, HorseState
+from .config import Config
+
+
+class RaceEngine:
+    def __init__(self, config: Config):
+        self.config = config
+        self.active_tasks: dict[str, asyncio.Task] = {}
+
+    async def start_race(self, room: Room) -> asyncio.Task:
+        """Start race progression loop."""
+        task = asyncio.create_task(self._race_loop(room))
+        self.active_tasks[room.scope] = task
+        return task
+
+    async def _race_loop(self, room: Room):
+        """Main race progression loop."""
+        room.state = RoomState.RUNNING
+
+        while room.state == RoomState.RUNNING:
+            await asyncio.sleep(self.config.RACE_TICK_INTERVAL)
+            room.tick_count += 1
+
+            for horse in room.horses.values():
+                if horse.state == HorseState.RACING:
+                    distance = max(0, random.gauss(10, 3))
+                    horse.position += distance
+
+            finished_horses = [
+                h for h in room.horses.values()
+                if h.position >= self.config.RACE_DISTANCE
+            ]
+
+            if finished_horses:
+                champion = self._determine_champion(finished_horses)
+                room.champion_name = champion.name
+                room.state = RoomState.FINISHED
+                break
+
+    def _determine_champion(self, horses: list[Horse]) -> Horse:
+        """Determine champion from tied horses."""
+        if len(horses) == 1:
+            return horses[0]
+
+        while len(horses) > 1:
+            distances = [max(0, random.gauss(10, 3)) for _ in horses]
+            max_distance = max(distances)
+            horses = [h for h, d in zip(horses, distances) if d == max_distance]
+
+        return horses[0]
+
+    def stop_race(self, scope: str):
+        """Stop race and cancel task."""
+        if scope in self.active_tasks:
+            task = self.active_tasks[scope]
+            if not task.done():
+                task.cancel()
+            del self.active_tasks[scope]