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/complex_item_drop_test.gd

@@ -12,6 +12,7 @@ const ExchangeUI = preload("res://ui/exchange_ui.gd")
 
 class FakeClient extends Node:
 	signal safebox_changed()
+	signal inventory_changed()
 	signal mall_opened(size: int)
 	signal mall_changed()
 	signal shop_opened(vid: int)
@@ -39,6 +40,7 @@ class FakeClient extends Node:
 		calls.append(["safe_move", src, dst, count]); return true
 	func safebox_checkout(src, window, cell) -> bool:
 		calls.append(["safe_checkout", src, window, cell]); return true
+	func get_inventory() -> Array: return []
 
 	func is_mall_open() -> bool: return mall_open
 	func get_mall_size() -> int: return mall_size
@@ -91,11 +93,11 @@ func _init() -> void:
 			"inventory item drops into empty safebox slot")
 	_ck(_has_call(client, "safe_checkin", func(c): return c[1] == 4 and c[2] == 1 and c[3] == 7),
 			"safebox drop uses explicit destination slot")
-	var safe_item := safe._cells[2] as Button
+	var safe_item := safe._cells[2] as Control
 	var safe_event := InputEventMouseButton.new()
 	safe_event.button_index = MOUSE_BUTTON_LEFT
 	safe_event.pressed = true
-	safe._on_grid_input(2, safe_event)
+	safe._on_cell_input(2, safe_event)
 	_ck(mouse.is_attached() and int(mouse.attached().get("window", -1)) == 3,
 			"safebox item enters global item state")
 	mouse.cancel()