feat(前端界面): 精简系统字体按钮文案，优化侧栏排版

assets/webui/index.html

@@ -125,7 +125,7 @@
 						<div id="fontPanelTitle" class="panel-title compact">可用字体</div>
 						<div class="panel-actions">
 							<span id="availableFontSummary" class="count-pill">0</span>
-							<button id="localFontButton" class="small-button" type="button">系统字体</button>
+							<button id="localFontButton" class="small-button" type="button" aria-label="系统字体">系统</button>
 							<button id="fontAddButton" class="small-button" type="button">添加</button>
 							<button id="fontDirectoryButton" class="small-button" type="button" title="添加字体目录" aria-label="添加字体目录">目录</button>
 						</div>