新增 CardBase 组件，重构知识文档卡片、知识库卡片和分段卡片以使用新组件，优化按钮组件并更新相关页面以提升用户体验。

frontend/src/components/ui/Button.vue

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+<template>
+  <button :class="[
+    'flex items-center justify-center gap-x-1 whitespace-nowrap font-medium rounded-lg focus:ring-4 focus:outline-none',
+    sizeClasses,
+    colorClasses,
+    (disabled || (isLoading && !abortable)) ? 'opacity-50 cursor-not-allowed' : '',
+    fullWidth ? 'w-full' : '',
+    className
+  ]" :disabled="disabled || (isLoading && !abortable)" @click="handleClick" :type="type">
+    <div v-if="isLoading && !abortable" class="animate-spin mr-1" :class="iconSizeClasses">
+      <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24">
+        <circle class="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" stroke-width="4"></circle>
+        <path class="opacity-75" fill="currentColor"
+          d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z">
+        </path>
+      </svg>
+    </div>
+    <StopIcon v-else-if="isLoading && abortable" :class="iconSizeClasses" />
+    <slot v-else name="icon"></slot>
+    <span v-if="$slots.default">
+      <slot></slot>
+    </span>
+  </button>
+</template>
+
+<script setup lang="ts">
+import { StopIcon } from "@/components/icons";
+import { computed } from "vue";
+
+export type ButtonVariant =
+  | "primary"
+  | "secondary"
+  | "success"
+  | "danger"
+  | "warning"
+  | "info";
+export type ButtonSize = "xs" | "sm" | "md" | "lg";
+export type ButtonType = "button" | "submit" | "reset";
+
+const props = defineProps<{
+  /** 按钮变体类型 */
+  variant?: ButtonVariant;
+  /** 按钮尺寸 */
+  size?: ButtonSize;
+  /** 是否禁用 */
+  disabled?: boolean;
+  /** 自定义CSS类名 */
+  className?: string;
+  /** 是否为移动端尺寸 */
+  isMobile?: boolean;
+  /** 是否处于加载状态 */
+  isLoading?: boolean;
+  /** 是否可中止 */
+  abortable?: boolean;
+  /** 按钮类型 */
+  type?: ButtonType;
+  /** 是否占满宽度 */
+  fullWidth?: boolean;
+}>();
+
+const emit = defineEmits<{
+  click: [event: MouseEvent];
+}>();
+
+/** 按钮颜色样式映射 */
+const colorClasses = computed(() => {
+  const variants: Record<ButtonVariant, string> = {
+    primary: "text-white bg-blue-700 hover:bg-blue-800 focus:ring-blue-300",
+    secondary:
+      "text-gray-900 bg-white border border-gray-300 hover:bg-gray-100 focus:ring-gray-100",
+    success: "text-white bg-green-700 hover:bg-green-800 focus:ring-green-300",
+    danger: "text-white bg-red-700 hover:bg-red-800 focus:ring-red-300",
+    warning:
+      "text-gray-900 bg-yellow-400 hover:bg-yellow-500 focus:ring-yellow-300",
+    info: "text-white bg-cyan-700 hover:bg-cyan-800 focus:ring-cyan-300",
+  };
+
+  return variants[props.variant || "primary"];
+});
+
+/** 按钮尺寸样式映射 */
+const sizeClasses = computed(() => {
+  // 移动端尺寸
+  if (props.isMobile) {
+    const sizes: Record<ButtonSize, string> = {
+      xs: "text-xs px-2 py-1",
+      sm: "text-xs px-3 py-1.5",
+      md: "text-sm px-3 py-2",
+      lg: "text-sm px-4 py-2.5",
+    };
+    return sizes[props.size || "sm"];
+  }
+
+  // PC端尺寸
+  const sizes: Record<ButtonSize, string> = {
+    xs: "text-xs px-3 py-1.5",
+    sm: "text-sm px-3 py-2",
+    md: "text-sm px-4 py-2.5",
+    lg: "text-base px-5 py-3",
+  };
+
+  return sizes[props.size || "md"];
+});
+
+/** 图标尺寸样式映射 */
+const iconSizeClasses = computed(() => {
+  const sizes: Record<ButtonSize, string> = {
+    xs: "w-3.5 h-3.5",
+    sm: "w-4 h-4",
+    md: "w-4.5 h-4.5",
+    lg: "w-5 h-5",
+  };
+  return sizes[props.size || "md"];
+});
+
+/** 处理点击事件 */
+const handleClick = (event: MouseEvent) => {
+  if (!props.disabled && !(props.isLoading && !props.abortable)) {
+    emit("click", event);
+  }
+};
+</script>