feat: 支持自定义引用消息样式

允许用户在设置中切换引用消息与正文的上下顺序，并使聊天页中的引用回复即时按所选样式展示。
  Close#510

src/pages/SettingsPage.scss

@@ -1145,6 +1145,134 @@
   }
 }
 
+.quote-layout-picker {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
+  gap: 12px;
+  margin-top: 10px;
+}
+
+.quote-layout-card {
+  position: relative;
+  border: 1px solid var(--border-color);
+  border-radius: 16px;
+  padding: 14px;
+  background: var(--bg-primary);
+  color: inherit;
+  cursor: pointer;
+  text-align: left;
+  transition: border-color 0.2s ease, box-shadow 0.2s ease, transform 0.2s ease, background 0.2s ease;
+
+  &:hover {
+    border-color: color-mix(in srgb, var(--primary) 35%, var(--border-color));
+    transform: translateY(-1px);
+  }
+
+  &.active {
+    border-color: var(--primary);
+    box-shadow: 0 0 0 3px color-mix(in srgb, var(--primary) 14%, transparent);
+    background: color-mix(in srgb, var(--bg-primary) 92%, var(--primary) 8%);
+  }
+}
+
+.quote-layout-card-header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 12px;
+  margin-bottom: 12px;
+}
+
+.quote-layout-card-title-group {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
+.quote-layout-card-title {
+  font-size: 14px;
+  font-weight: 600;
+  color: var(--text-primary);
+}
+
+.quote-layout-card-desc {
+  font-size: 12px;
+  color: var(--text-tertiary);
+}
+
+.quote-layout-card-check {
+  width: 22px;
+  height: 22px;
+  border-radius: 50%;
+  border: 1px solid var(--border-color);
+  color: transparent;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  transition: all 0.2s ease;
+
+  &.active {
+    border-color: var(--primary);
+    background: var(--primary);
+    color: #fff;
+  }
+}
+
+.quote-layout-preview {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  padding: 12px;
+  border-radius: 12px;
+  background: color-mix(in srgb, var(--bg-secondary) 92%, var(--bg-primary));
+  border: 1px solid color-mix(in srgb, var(--border-color) 70%, transparent);
+  min-height: 112px;
+
+  &.quote-bottom {
+    .quote-layout-preview-message {
+      order: 1;
+    }
+
+    .quote-layout-preview-quote {
+      order: 2;
+    }
+  }
+}
+
+.quote-layout-preview-quote {
+  padding: 8px 10px;
+  border-left: 2px solid var(--primary);
+  border-radius: 8px;
+  background: rgba(0, 0, 0, 0.04);
+  display: flex;
+  flex-direction: column;
+  gap: 3px;
+}
+
+.quote-layout-preview-sender {
+  font-size: 12px;
+  font-weight: 600;
+  color: var(--primary);
+}
+
+.quote-layout-preview-text {
+  font-size: 12px;
+  color: var(--text-secondary);
+  line-height: 1.4;
+}
+
+.quote-layout-preview-message {
+  align-self: flex-start;
+  max-width: 88%;
+  padding: 9px 12px;
+  border-radius: 12px;
+  background: color-mix(in srgb, var(--primary) 14%, var(--bg-primary));
+  color: var(--text-primary);
+  font-size: 13px;
+  line-height: 1.45;
+}
+
 .theme-grid {
   display: grid;
   grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));