fix(battle): correct killer name in death handling logic

- Updated the killer name reference in the handle_death function to use the winner's name instead of the attacker's name, ensuring accurate death reason reporting in battle scenarios.

src/classes/battle.py

@@ -304,5 +304,5 @@ async def handle_battle_finish(
     
     # 处理死亡
     if is_fatal:
-        handle_death(world, loser, DeathReason(DeathType.BATTLE, killer_name=attacker.name))
+        handle_death(world, loser, DeathReason(DeathType.BATTLE, killer_name=winner.name))
     return [result_event, story_event]

tests/test_battle_death.py

@@ -0,0 +1,54 @@
+import pytest
+from unittest.mock import MagicMock, AsyncMock, patch
+from src.classes.battle import handle_battle_finish
+from src.classes.death_reason import DeathType
+
+@pytest.mark.asyncio
+async def test_attacker_dies_killer_is_winner():
+    # Setup mocks
+    world = MagicMock()
+    world.month_stamp = 100
+
+    attacker = MagicMock()
+    attacker.id = "attacker"
+    attacker.name = "Attacker"
+    attacker.hp = -10 # Dead
+
+    defender = MagicMock()
+    defender.id = "defender"
+    defender.name = "Defender"
+    defender.hp = 50 # Alive
+
+    # res: (winner, loser, loser_damage, winner_damage)
+    # Defender wins, Attacker loses
+    res = (defender, attacker, 110, 10)
+
+    start_content = "Battle start"
+    story_prompt = "Story prompt"
+
+    # Patch StoryTeller and handle_death
+    with patch("src.classes.story_teller.StoryTeller.tell_story", new_callable=AsyncMock) as mock_tell_story, \
+         patch("src.classes.death.handle_death") as mock_handle_death:
+        
+        mock_tell_story.return_value = "Story content"
+
+        await handle_battle_finish(
+            world,
+            attacker,
+            defender,
+            res,
+            start_content,
+            story_prompt
+        )
+
+        # Assert handle_death called
+        assert mock_handle_death.called
+
+        # Get the DeathReason object passed to handle_death
+        # handle_death(world, loser, death_reason)
+        call_args = mock_handle_death.call_args
+        death_reason = call_args[0][2]
+
+        assert death_reason.death_type == DeathType.BATTLE
+        # This is the bug: it was attacker.name (Attacker), should be winner.name (Defender)
+        assert death_reason.killer_name == defender.name