feat(武器): 增强氧炔枪属性并更新描述

调整氧炔枪的攻击属性：
- 基础攻击加成从0.3提升至0.5
- 火焰攻击加成从0.1提升至0.25
- 浓硝酸液滴的生存时间减半
更新武器描述文本，明确说明火焰的击退效果和浓硝酸的射程较短特性

scripts/Contents/Weapons/Oxygener.gd

@@ -2,8 +2,8 @@
 extends Weapon
 
 func update(to: int, origin: Dictionary, _entity: EntityBase):
-    origin["atk"] += 0.3 * to * soulLevel
-    origin["fireatk"] += 0.1 * to * soulLevel
+    origin["atk"] += 0.5 * to * soulLevel
+    origin["fireatk"] += 0.25 * to * soulLevel
     origin["max-n"] *= soulLevel
     return origin
 func attack(entity: EntityBase):
@@ -19,3 +19,4 @@ func attack(entity: EntityBase):
                 bullet.baseDamage = readStore("fireatk")
             elif bullet is AcidN:
                 bullet.baseDamage = readStore("atk")
+                bullet.lifeTime *= 0.5