Implement asset upload API and utility functions

- Add Asset and CardLayer model updates
- Create asset upload API endpoints
- Add AssetUploadDialog component
- Create card layout algorithms
- Implement symmetry generation utils
- Add template configurations

frontend/src/components/AssetUploadDialog.vue

@@ -0,0 +1,154 @@
+<template>
+  <el-dialog
+    v-model="dialogVisible"
+    title="上传素材"
+    width="500px"
+    @close="handleClose"
+  >
+    <el-form :model="form" label-width="100px">
+      <el-form-item label="素材类型">
+        <el-select v-model="form.assetType" placeholder="选择素材类型">
+          <el-option label="花色图案" value="suit_symbol" />
+          <el-option label="JQK人像" value="face_card" />
+          <el-option label="大小王" value="joker" />
+          <el-option label="背面图案" value="back" />
+        </el-select>
+      </el-form-item>
+
+      <el-form-item label="素材标识">
+        <el-input
+          v-model="form.assetKey"
+          placeholder="如：spade, heart-J, big_joker"
+        />
+      </el-form-item>
+
+      <el-form-item label="选择文件">
+        <el-upload
+          ref="upload"
+          drag
+          :auto-upload="false"
+          :on-change="handleFileChange"
+          :limit="1"
+          :on-exceed="handleExceed"
+        >
+          <el-icon class="el-icon--upload"><upload-filled /></el-icon>
+          <div class="el-upload__text">
+            拖拽文件到此处或<em>点击上传</em>
+          </div>
+          <template #tip>
+            <div class="el-upload__tip">
+              支持 PNG, JPG, SVG 格式
+            </div>
+          </template>
+        </el-upload>
+      </el-form-item>
+    </el-form>
+
+    <template #footer>
+      <el-button @click="handleClose">取消</el-button>
+      <el-button
+        type="primary"
+        :loading="uploading"
+        :disabled="!canSubmit"
+        @click="handleSubmit"
+      >
+        上传
+      </el-button>
+    </template>
+  </el-dialog>
+</template>
+
+<script setup>
+import { ref, computed, watch } from 'vue'
+import { ElMessage } from 'element-plus'
+import { UploadFilled } from '@element-plus/icons-vue'
+import { uploadAsset } from '@/api/asset'
+
+const props = defineProps({
+  modelValue: Boolean,
+  projectId: String
+})
+
+const emit = defineEmits(['update:modelValue', 'upload-success'])
+const dialogVisible = ref(props.modelValue)
+const upload = ref(null)
+const uploading = ref(false)
+const selectedFile = ref(null)
+
+const form = ref({
+  assetType: 'suit_symbol',
+  assetKey: '',
+  file: null
+})
+
+const canSubmit = computed(() => {
+  return form.value.assetKey && selectedFile.value
+})
+
+watch(() => props.modelValue, (val) => {
+  dialogVisible.value = val
+})
+
+watch(dialogVisible, (val) => {
+  emit('update:modelValue', val)
+})
+
+function handleFileChange(file) {
+  selectedFile.value = file.raw
+}
+
+function handleExceed() {
+  ElMessage.warning('只能上传一个文件')
+}
+
+async function handleSubmit() {
+  if (!canSubmit.value) {
+    ElMessage.warning('请填写完整信息')
+    return
+  }
+
+  try {
+    uploading.value = true
+    await uploadAsset(
+      props.projectId,
+      selectedFile.value,
+      form.value.assetType,
+      form.value.assetKey
+    )
+
+    ElMessage.success('上传成功')
+    emit('upload-success')
+    handleClose()
+  } catch (error) {
+    ElMessage.error('上传失败')
+    console.error(error)
+  } finally {
+    uploading.value = false
+  }
+}
+
+function handleClose() {
+  dialogVisible.value = false
+  emit('update:modelValue', false)
+  // Reset form
+  form.value = {
+    assetType: 'suit_symbol',
+    assetKey: '',
+    file: null
+  }
+  selectedFile.value = null
+}
+</script>
+
+<style scoped>
+.el-upload__text {
+  color: #606266;
+  font-size: 14px;
+}
+
+.el-upload__tip {
+  color: #909399;
+  font-size: 12px;
+  margin-top: 8px;
+}
+</style>