feat(webui): vue admin panel source

Vue 3 + TypeScript + Pinia + Tailwind v4 + shadcn-vue + Chart.js admin
panel source under webui/, built with Vite. Views: Overview (providers,
redis/cache/retry status, model aliases), Usage (per-user/per-group/total
tables with tokensIn/tokensOut/cost + limits), Charts (scope selector,
req/tokens(stacked in-out)/cost metric tabs, 24h/30d/12mo window
switcher, fed by GET /admin/api/usage/history). Pinia stores: auth
(sessionStorage key gate, x-api-key header, 401/403 re-prompt),
dashboard (5s poll), history (fetch-on-selection + 30s refresh).

Design: deliberate neutral warm-neutral palette with a signature teal
accent (no default Inter/purple-gradient/glassmorphism), real
typographic hierarchy via the platform UI/mono font stacks (zero
external assets - no Google Fonts), dark+light via prefers-color-scheme
(no class toggle, no theme switcher). Charts: zero-based bars, honest
axes, Okabe-Ito colorblind-safe series, tokens-in/out as a
distinguishable stacked pair.

vite.config.ts: base '/admin/' (matches admin.go's route layout) and
build.modulePreload.polyfill:false (no inline bootstrap script, so the
tightened admin CSP needs no 'unsafe-inline'). Code-split: Chart.js
(ChartsView) loads lazily, not in the initial bundle.

generate.mjs reads dist/ after `vite build` and writes
../admin_assets_gen.go (not committed by this change) - base64-encodes
every asset, decoded once at package-var init; documented rationale in
the script's own header comment.

Hygiene: webui/go.mod walls webui/ off from the repo root's `go build`/
`vet`/`test ./...` (npm's node_modules bundles a stray .go file that
would otherwise be swept in); tools/yaegi-check/main.go excludes webui/
from its GOPATH copy for the same reason. webui/ export-ignored
(.gitattributes) from release source tarballs; webui/node_modules/
gitignored. tsconfig.app.json/tsconfig.node.json's JSONC comments
dropped (TS itself is fine with either; the global pre-commit JSON
validator is not) - no config values changed.

webui/src/types/api.ts

@@ -0,0 +1,103 @@
+// Shared response shapes for the three /admin/api/* routes (admin.go). Kept
+// as one module so every store/component imports the identical types rather
+// than re-declaring them (vue.md: "share types once, import everywhere").
+
+/** Mirrors Go's LimitsConfig (llmgateway.go) — every field is 0/omitted when unlimited. */
+export interface LimitsConfig {
+  requestsPerMinute?: number
+  requestsPerDay?: number
+  tokensPerDay?: number
+  tokensPerMonth?: number
+  costPerDayUSD?: number
+  costPerMonthUSD?: number
+}
+
+export interface AdminProviderView {
+  name: string
+  type: string
+  baseUrl: string
+  lastRefresh: string
+  lastErr?: string
+  modelCount: number
+}
+
+export interface AdminRedisView {
+  lastErrAt: string
+  lastErr?: string
+  configured: boolean
+}
+
+export interface AdminCacheView {
+  ttl?: string
+  enabled: boolean
+}
+
+export interface AdminRetryView {
+  backoff?: string
+  enabled: boolean
+  attempts?: number
+}
+
+export interface AdminGroupView {
+  limits?: LimitsConfig
+  name: string
+  memberCount: number
+}
+
+export interface AdminAliasView {
+  alias: string
+  target: string
+}
+
+/** GET /admin/api/overview (admin.go: adminOverviewResponse). */
+export interface AdminOverviewResponse {
+  version: string
+  providers: AdminProviderView[]
+  groups: AdminGroupView[]
+  aliases: AdminAliasView[]
+  redis: AdminRedisView
+  cache: AdminCacheView
+  retry: AdminRetryView
+}
+
+export interface AdminUsageEntryView {
+  limits?: LimitsConfig
+  kind: string
+  id: string
+  groupName?: string
+  requestsPerMinute: number
+  requestsPerDay: number
+  tokensInPerDay: number
+  tokensOutPerDay: number
+  tokensInPerMonth: number
+  tokensOutPerMonth: number
+  costPerDayMicroUsd: number
+  costPerMonthMicroUsd: number
+  storeDown?: boolean
+}
+
+/** GET /admin/api/usage (admin.go: adminUsageResponse). */
+export interface AdminUsageResponse {
+  users: AdminUsageEntryView[]
+  groups: AdminUsageEntryView[]
+  total: AdminUsageEntryView
+}
+
+/** The four metric values GET /admin/api/usage/history accepts. */
+export type HistoryMetric = 'req' | 'tokin' | 'tokout' | 'cost'
+
+/** The three window values GET /admin/api/usage/history accepts. */
+export type HistoryWindow = 'hour' | 'day' | 'month'
+
+export interface UsageHistoryPoint {
+  bucket: string
+  value: number
+}
+
+/** GET /admin/api/usage/history (admin.go: usageHistoryResponse). */
+export interface UsageHistoryResponse {
+  scope: string
+  metric: string
+  window: string
+  points: UsageHistoryPoint[]
+}