feat: initial commit - oncology literature search platform

OncoLit: a multi-tenant oncology literature search, feed, and
collaboration platform. Built with FastAPI + Vue 3 + PostgreSQL.
Includes PubMed pipeline, drug approvals, AI summaries, and
systematic review tools.

frontend/src/composables/useApiRequest.ts

@@ -0,0 +1,25 @@
+import { ref, readonly, type Ref } from 'vue'
+
+export function useApiRequest<T>(fetcher: (...args: any[]) => Promise<T>) {
+  const data: Ref<T | null> = ref(null)
+  const loading = ref(false)
+  const error = ref<string | null>(null)
+
+  async function execute(...args: any[]): Promise<T | null> {
+    loading.value = true
+    error.value = null
+    try {
+      const result = await fetcher(...args)
+      data.value = result
+      return result
+    } catch (e: any) {
+      const msg = e?.response?.data?.detail || e?.message || '请求失败'
+      error.value = msg
+      return null
+    } finally {
+      loading.value = false
+    }
+  }
+
+  return { data: readonly(data), loading: readonly(loading), error: readonly(error), execute }
+}