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Chart and ranking fetches carry a request id, and a superseded response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/vite.config.ts

@@ -32,6 +32,24 @@ export default defineConfig({
     // polyfill has nothing to do here anyway.
     modulePreload: { polyfill: false },
   },
+  server: {
+    // `npm run dev` serves this app at :5173 (or whatever Vite picks), but
+    // every fetch('/admin/api/...') (lib/api.ts) is a same-origin, relative
+    // path — without a proxy it hits Vite itself, which has no such route
+    // and answers with a 404 or the index.html SPA fallback, so the dev
+    // build can never actually load data. Proxying just the API path (not
+    // '/admin' itself) leaves Vite serving this project's own index.html/
+    // HMR client at '/admin/' as usual. The target is env-configurable
+    // (ADMIN_API_PROXY_TARGET) rather than hardcoded, since which gateway
+    // instance a developer is pointed at varies by machine; the fallback
+    // matches this repo's own `run-local`/integration default port.
+    proxy: {
+      '/admin/api': {
+        target: process.env.ADMIN_API_PROXY_TARGET ?? 'http://localhost:8080',
+        changeOrigin: true,
+      },
+    },
+  },
   test: {
     // Deliberately narrow: lib/'s pure modules (search-expand.ts,
     // usage-search.ts) plus, since review round 2 (v0.21), stores/