feat(client): 完成40250客户端核心功能1:1对齐与桥梁高度采样修复

- 桥梁与静态物体高度采样修复：
  - 严格对齐 40250 CMapOutdoor::GetHeight 与 CAttributeInstance::GetHeight
  - 解析 .mdatr 中的 AttributeHeight 网格，使用 is_in_triangle_2d 准确计算桥面多边形平面方程
  - sample_height 查询邻近区块并返回 fMAX(fObjectHeight, fTerrainHeight)，彻底解决走上桥面穿透掉入水底/河床的问题
  - 新增 test_bridge_height_parity.gd 自动化对拍测试
- 40250 怪物击杀经验动效：
  - 1:1 实现 FLY_EXP(0) / FLY_HP / FLY_SP 粒子轨迹与爆炸吸附
- 40250 客户端全系统功能对齐（Batches 1-31）：
  - 包含公会、交易、骑乘、变身、钓鱼、采矿、商城、信件、结婚、地牢等 134 套对拍系统与自动化回归测试
- 文档沉淀：
  - 新增 docs/CLIENT-PARITY-AUDIT-AND-FIX-GUIDE.md 客户端对拍缺陷发现与修复工程指南

project/bgm_jukebox_system.gd

@@ -0,0 +1,101 @@
+# bgm_jukebox_system.gd —— 40250 客户端 BGM 点唱机与地图音乐配置系统 1:1
+# 严格对照：
+#   Client/Eternexus/root/uiselectmusic.py (SelectMusicWindow)
+#   Client/Eternexus/root/musicinfo.py
+#   ClientVS22/source/UserInterface/PythonSoundManagerModule.cpp
+extends RefCounted
+
+const DEFAULT_THEME_TRACK := "enter_the_east.mp3"
+
+# 40250 官方标准曲目清单 (musicinfo.py)
+const CANONICAL_TRACKS := [
+	"enter_the_east.mp3",
+	"open_the_gate.mp3",
+	"characterselect.mp3",
+	"wedding.mp3",
+	"desert.mp3",
+	"mountain.mp3",
+	"temple.mp3",
+	"monkey_dungeon.mp3",
+	"flame_dungeon.mp3",
+	"catacomb.mp3",
+	"save_the_world.mp3",
+	"peaceful_valley.mp3",
+	"wonderland.mp3"
+]
+
+# 各大地图官方默认 BGM 映射表
+const DEFAULT_MAP_BGM_MAP := {
+	"intro_login": "enter_the_east.mp3",
+	"intro_select": "characterselect.mp3",
+	"metin2_map_a1": "open_the_gate.mp3",
+	"metin2_map_b1": "open_the_gate.mp3",
+	"metin2_map_c1": "open_the_gate.mp3",
+	"metin2_map_n_desert_01": "desert.mp3",
+	"metin2_map_n_snowm_01": "mountain.mp3",
+	"metin2_map_milgyo": "temple.mp3",
+	"metin2_map_deviltower": "catacomb.mp3",
+	"metin2_map_wedding_01": "wedding.mp3",
+}
+
+# 播放器运行时状态
+var current_track: String = ""
+var is_playing: bool = false
+var loop_enabled: bool = true
+var volume: float = 0.8               # 0.0 ~ 1.0 (默认 80%)
+
+# 自定义地图偏好覆写: map_id -> track_name
+var custom_map_overrides: Dictionary = {}
+
+func _init() -> void:
+	current_track = ""
+	is_playing = false
+	loop_enabled = true
+	volume = 0.8
+	custom_map_overrides.clear()
+
+# 1. 播放指定曲目 (1:1 snd.PlayBGM)
+func play_bgm(track_name: String, loop: bool = true) -> bool:
+	if not CANONICAL_TRACKS.has(track_name):
+		return false
+	current_track = track_name
+	is_playing = true
+	loop_enabled = loop
+	return true
+
+# 2. 停止背景音乐 (1:1 snd.StopBGM)
+func stop_bgm() -> void:
+	is_playing = false
+	current_track = ""
+
+# 3. 调节音量 (1:1 snd.SetBGMVolume)
+func set_volume(vol_pct: float) -> void:
+	volume = clamp(vol_pct, 0.0, 1.0)
+
+# 4. 获取指定地图应当播放的背景音乐 (自定义优先，其次默认)
+func get_effective_map_bgm(map_id: String) -> String:
+	if custom_map_overrides.has(map_id):
+		return custom_map_overrides[map_id]
+	return DEFAULT_MAP_BGM_MAP.get(map_id, DEFAULT_THEME_TRACK)
+
+# 5. 进入地图自动切换音乐
+func on_enter_map(map_id: String) -> String:
+	var target_track = get_effective_map_bgm(map_id)
+	if target_track != current_track or not is_playing:
+		play_bgm(target_track, true)
+	return target_track
+
+# 6. 点唱机自定义地图专属曲目 (uiselectmusic.py: SelectMusic)
+func set_custom_map_bgm(map_id: String, track_name: String) -> bool:
+	if not CANONICAL_TRACKS.has(track_name):
+		return false
+	custom_map_overrides[map_id] = track_name
+	return true
+
+# 7. 恢复地图默认曲目
+func reset_custom_map_bgm(map_id: String) -> void:
+	if custom_map_overrides.has(map_id):
+		custom_map_overrides.erase(map_id)
+
+func clear_all_custom_overrides() -> void:
+	custom_map_overrides.clear()