fix(webui): keep charts consistent with the current selection

Chart and ranking fetches carry a request id, and a superseded response
is dropped. Changing a selection clears the old data at once, so old
numbers never show under new labels or units. The auto-refresh tick
skips while a fetch is still in flight. "Loading..." shows only until
the first result for a selection arrives. Dashboard polls do not
overlap.

Users in several groups are counted and searched in every group. The
Models tab labels its windows as the current UTC bucket. Hour labels
are marked UTC. The Members column sorts numerically. Target access
shows "All groups" for null and "No groups" for []. The UI shows the
server's own error message. Cost axis ticks use the currency
formatter. npm run dev proxies /admin/api. Nine unused shadcn
components are removed.

admin_assets_gen.go is regenerated from the new build.

Claude-Session: https://claude.ai/code/session_01V5jYJNxpDFdJkyyExpADrv

webui/src/App.vue

@@ -41,6 +41,12 @@ type TabValue = (typeof TAB_VALUES)[number]
 // authenticated transition with no extra wiring here.
 const activeView = useTabHash<TabValue>({ validTabs: TAB_VALUES, defaultTab: 'providers' })
 
+// statusText reads dashboard.error/lastUpdated unconditionally — it is
+// correct only while the template's own `v-if="auth.isAuthenticated"` below
+// keeps it off-screen otherwise. Without that gate a 401 (which resolves
+// before touching error/lastUpdated) left the PRIOR "last updated ..." or
+// "refresh failed: ..." line showing right under the auth gate, and a first
+// load with no stored key showed "loading..." forever (review finding).
 const statusText = computed<string>(() => {
   if (dashboard.error) return `refresh failed: ${dashboard.error}`
   if (dashboard.lastUpdated) return `last updated ${dashboard.lastUpdated.toLocaleTimeString()}`
@@ -70,7 +76,7 @@ onMounted(() => {
           <FontAwesomeIcon :icon="faGithub" class="size-4" aria-hidden="true" />
         </Button>
       </div>
-      <p class="flex items-center gap-1.5 text-sm text-muted-foreground">
+      <p v-if="auth.isAuthenticated" class="flex items-center gap-1.5 text-sm text-muted-foreground">
         <FontAwesomeIcon v-if="dashboard.error" :icon="faCircleExclamation" class="size-3.5 text-destructive" />
         <span :class="dashboard.error ? 'text-destructive' : undefined">{{ statusText }}</span>
       </p>