管理后台用量统计支持按用户筛选：用户名输入 + datalist 自动补全，精确匹配解析为 user_id

- types: UsageLog 补 user_id 字段
- UsageView: 新增用户筛选输入框，防抖 300ms 拉取 admin/users 候选做下拉补全
- search 时将用户名经 admin/users 精确解析为 user_id 再过滤 admin/usage；未找到用户时 toast 报错
- 支持清除筛选一键还原

web/src/types.ts

@@ -94,6 +94,7 @@ export interface UsageLog {
   raw_response?: string
   created_at: string
   user?: string
+  user_id?: number
 }
 
 export interface Paged<T> {

web/src/views/admin/UsageView.vue

@@ -7,13 +7,16 @@ import { fmtCost, fmtTime } from '@/lib/format'
 import Badge from '@/components/ui/Badge.vue'
 import Button from '@/components/ui/Button.vue'
 import Modal from '@/components/ui/Modal.vue'
-import type { UsageLog } from '@/types'
+import type { UsageLog, User } from '@/types'
 
 const toast = useToastStore()
 const logs = ref<UsageLog[]>([])
 const total = ref(0)
 const page = ref(1)
 const modelFilter = ref('')
+const userFilter = ref('')
+const userCandidates = ref<User[]>([])
+let userSearchTimer: ReturnType<typeof setTimeout> | null = null
 const pageSize = 15
 
 const viewing = ref<UsageLog | null>(null)
@@ -24,11 +27,47 @@ function openRaw(l: UsageLog) {
   viewTab.value = 'request'
 }
 
+// 用户自动补全候选（防抖 300ms）
+function onUserInput() {
+  if (userSearchTimer) clearTimeout(userSearchTimer)
+  const kw = userFilter.value.trim()
+  if (!kw) {
+    userCandidates.value = []
+    return
+  }
+  userSearchTimer = setTimeout(async () => {
+    try {
+      const { data } = await http.get(`/admin/users?q=${encodeURIComponent(kw)}&page_size=10`)
+      userCandidates.value = data.data.items ?? []
+    } catch {
+      userCandidates.value = []
+    }
+  }, 300)
+}
+
+// 用户名 → user_id（精确匹配），查不到返回 null
+async function resolveUserId(username: string): Promise<number | null> {
+  const { data } = await http.get(`/admin/users?q=${encodeURIComponent(username)}&page_size=10`)
+  const items: User[] = data.data.items ?? []
+  const hit = items.find((u) => u.username === username)
+  return hit ? hit.id : null
+}
+
 async function load() {
   try {
-    const { data } = await http.get(
-      `/admin/usage?page=${page.value}&page_size=${pageSize}${modelFilter.value ? '&model=' + modelFilter.value : ''}`,
-    )
+    const params = new URLSearchParams()
+    params.set('page', String(page.value))
+    params.set('page_size', String(pageSize))
+    if (modelFilter.value.trim()) params.set('model', modelFilter.value.trim())
+    if (userFilter.value.trim()) {
+      const uid = await resolveUserId(userFilter.value.trim())
+      if (uid === null) {
+        toast.err(`未找到用户：${userFilter.value.trim()}`)
+        return
+      }
+      params.set('user_id', String(uid))
+    }
+    const { data } = await http.get(`/admin/usage?${params.toString()}`)
     logs.value = data.data.items
     total.value = data.data.total
   } catch (e) {
@@ -41,6 +80,12 @@ function search() {
   load()
 }
 
+function clearUser() {
+  userFilter.value = ''
+  userCandidates.value = []
+  search()
+}
+
 function goPage(p: number) {
   page.value = p
   load()
@@ -56,7 +101,28 @@ onMounted(load)
         <h1 class="text-lg font-semibold">用量统计</h1>
         <p class="text-sm text-muted">全局请求明细与成本</p>
       </div>
-      <div class="flex gap-2">
+      <div class="flex flex-wrap gap-2">
+        <div class="relative">
+          <input
+            v-model="userFilter"
+            list="user-options"
+            placeholder="按用户过滤"
+            class="h-10 w-44 rounded-md border border-edge2 bg-surface px-3 font-mono text-xs outline-none focus:border-accent"
+            @input="onUserInput"
+            @keyup.enter="search"
+          />
+          <button
+            v-if="userFilter"
+            class="absolute right-2 top-1/2 -translate-y-1/2 text-xs text-muted hover:text-ink"
+            title="清除用户筛选"
+            @click="clearUser"
+          >
+            ✕
+          </button>
+        </div>
+        <datalist id="user-options">
+          <option v-for="u in userCandidates" :key="u.id" :value="u.username" />
+        </datalist>
         <input
           v-model="modelFilter"
           placeholder="按模型过滤"