fix: 修复 Markdown 编辑器容器高度和布局问题

src/lib/components/admin/MarkdownEditor.svelte

@@ -377,6 +377,18 @@
 
 	.editor-container {
 		width: 100%;
+		min-height: 400px;
+		display: flex;
+		flex-direction: column;
+	}
+
+	.editor-container :global(.cm-editor) {
+		flex: 1;
+		height: 100%;
+	}
+
+	.editor-container :global(.cm-scroller) {
+		align-items: stretch !important;
 	}
 
 	.md-toolbar {