feat: 提交流程中心前端代码

Vue3 + Vite + view-ui-plus 前端源码，含流程工作台、实例详情、
任务处理、管理端（定义/实例/映射/回调）等页面。
保留远程 .gitea/workflows/build.yml CI 配置。

src/components/BschSubjectSelect.vue

@@ -0,0 +1,37 @@
+<template>
+    <Select v-model="innerId" @on-change="handleChange" v-bind="$attrs">
+        <Option v-for="item in stageSubjects" :key="item.k" :value="item.k">
+            {{ item.v }}
+        </Option>
+    </Select>
+</template>
+
+<script lang="ts" setup>
+import { useDefaultStore } from '@/store'
+
+const emit = defineEmits<{
+    'on-change': [stage: number, subject: string]
+}>()
+
+const store = useDefaultStore()
+const stageSubjects = computed(() => store.getStageSubjects)
+
+const innerId = ref<number | null>(null)
+
+const cacheKey = 'bsch.learnmanage.cur_subject_id';
+onMounted(async () => {
+    await nextTick()
+    if (!stageSubjects.value.length) return
+    const cached = sessionStorage.getItem(cacheKey)
+    const id = cached ? Number(cached) : stageSubjects.value[0]?.k;
+    if (id != null) innerId.value = id
+    handleChange(id)
+})
+
+function handleChange(val: number) {
+    const find = stageSubjects.value.find((i: any) => i.k === val)
+    if (!find) return
+    sessionStorage.setItem(cacheKey, String(val))
+    emit('on-change', find.stage, find.code)
+}
+</script>