feat(theme): 新增 BlueForest 官方深色主题样式

- 新增 BlueForest.qss，基于 Fusion 控件规格的纯配色深色主题
- 深蓝底色 + 亮青绿强调色，控件尺寸与 Fusion 风格保持一致
- 全局统一 selection-background-color 为 #2dd4bf
- 背景色分层：页面 > 头部栏 > 交互控件 > 弹出层 > 输入区
- Border 属性统一拆分为 style/color/width 三段式
- AppInitializer / ALSettingsWidget 配合主题加载

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/boot/AppInitializer.py

@@ -12,7 +12,11 @@ import os
 from PySide6.QtCore import QStandardPaths, QDir
 from PySide6.QtWidgets import QApplication
 
-from gui.ALSettingsWidget import _applyTheme
+from gui.ALSettingsWidget import (
+    _setActiveStyleName,
+    _applyTheme,
+    _applyQss,
+)
 from interfaces.ConfigProvider import CfgKey
 from managers.config.ConfigManager import instance as configInstance
 from managers.driver.WebDriverManager import instance as webdriverInstance
@@ -76,7 +80,10 @@ def _initializeAppearance(
     cfg = configInstance()
     saved_style = cfg.get(CfgKey.GLOBAL.APPEARANCE.STYLE, "Fusion")
     saved_theme = cfg.get(CfgKey.GLOBAL.APPEARANCE.THEME, "system")
+    saved_qss = cfg.get(CfgKey.GLOBAL.APPEARANCE.CUSTOM_QSS, "")
     app.setStyle(saved_style)
+    _setActiveStyleName(saved_style)
+    _applyQss(saved_qss)
     _applyTheme(saved_theme)
 
 def initializeApp(