feat(admin): GitHub OAuth login, admin whitelist and Nuxt WebUI

Add an admin WebUI (Nuxt static SPA in admin/, served via the ASSETS
binding) for managing routes and viewing send logs. Access is gated by
GitHub OAuth plus an ADMIN_USER_IDS whitelist with cookie sessions
(admin-session.ts). Expose routes/logs CRUD API (admin-routes.ts), add a
discord-link mapping in token-store.ts, and mount admin routes with an
SPA assets fallback in the server.

admin/pages/index.vue

@@ -0,0 +1,170 @@
+<template>
+  <div>
+    <header>
+      <div class="brand">
+        <div class="brand-mark">WH</div>
+        <div>
+          <h1>WebHooker</h1>
+          <span class="tagline">CONFIG CONSOLE</span>
+        </div>
+      </div>
+      <div class="head-actions">
+        <button v-if="!needLogin" class="btn btn-accent" @click="openNew">+ New Route</button>
+        <a v-if="!needLogin" class="btn btn-ghost" href="/admin/logout">Sign out</a>
+      </div>
+    </header>
+
+    <main>
+      <div v-if="needLogin" class="login">
+        <div class="login-card">
+          <h2>Config Console</h2>
+          <p v-if="forbidden">Access denied — this GitHub account is not in <code>ADMIN_USER_IDS</code>.</p>
+          <p v-else>Sign in with GitHub to manage routes.</p>
+          <a class="btn btn-accent btn-lg" href="/admin/login">Sign in with GitHub</a>
+        </div>
+      </div>
+
+      <template v-else>
+        <nav class="tabs">
+          <button class="tab" :class="{ active: view === 'routes' }" @click="switchView('routes')">
+            Routes
+          </button>
+          <button class="tab" :class="{ active: view === 'logs' }" @click="switchView('logs')">
+            Send Logs
+          </button>
+        </nav>
+
+        <template v-if="view === 'routes'">
+          <section class="toolbar">
+            <div>
+              <span class="kpi-label">ROUTES</span>
+              <span class="kpi">{{ routes.length }}</span>
+            </div>
+            <div class="status">
+              <span class="dot" :class="loading ? '' : 'ok'"></span>
+              <span>{{ loading ? "loading" : "connected" }}</span>
+            </div>
+          </section>
+
+          <p v-if="error" class="err">{{ error }}</p>
+
+          <section class="routes">
+            <RouteCard
+              v-for="(r, i) in routes"
+              :key="r.id"
+              :route="r"
+              :style="{ animationDelay: i * 45 + 'ms' }"
+              @toggle="onToggle"
+              @edit="openEdit"
+              @delete="onDelete"
+            />
+          </section>
+
+          <section v-if="!loading && !routes.length" class="empty">
+            <p>No routes configured yet.</p>
+            <button class="btn btn-accent" @click="openNew">Create your first route</button>
+          </section>
+        </template>
+
+        <template v-else>
+          <section class="toolbar">
+            <div class="status">
+              <span class="dot" :class="logsLoading ? '' : 'ok'"></span>
+              <span>{{ logsLoading ? "loading" : "connected" }}</span>
+            </div>
+          </section>
+          <SendLogs :logs="logs" :loading="logsLoading" @refresh="loadLogs" />
+        </template>
+      </template>
+    </main>
+
+    <RouteEditor
+      :open="editorOpen"
+      :route="editing"
+      :saving="saving"
+      @close="editorOpen = false"
+      @save="onSave"
+    />
+  </div>
+</template>
+
+<script setup lang="ts">
+import type { Route } from "~/types";
+
+const { routes, loading, needLogin, error, load, save } = useRoutesApi();
+const { push } = useToasts();
+const { logs, loading: logsLoading, load: loadLogs } = useSendLogs();
+
+const editorOpen = ref(false);
+const editing = ref<Route | null>(null);
+const saving = ref(false);
+const forbidden = ref(false);
+const view = ref<"routes" | "logs">("routes");
+
+onMounted(() => {
+  if (typeof window !== "undefined") {
+    const params = new URLSearchParams(window.location.search);
+    forbidden.value = params.get("error") === "forbidden";
+  }
+  load();
+  loadLogs();
+});
+
+function switchView(next: "routes" | "logs"): void {
+  view.value = next;
+  if (next === "routes") load();
+  if (next === "logs") loadLogs();
+}
+
+function openNew(): void {
+  editing.value = null;
+  editorOpen.value = true;
+}
+
+function openEdit(route: Route): void {
+  editing.value = route;
+  editorOpen.value = true;
+}
+
+async function onSave(route: Route): Promise<void> {
+  saving.value = true;
+  try {
+    let next: Route[];
+    if (editing.value) {
+      next = routes.value.map((r) => (r.id === editing.value!.id ? route : r));
+    } else {
+      if (routes.value.some((r) => r.id === route.id)) {
+        push("Route ID already exists", "bad");
+        return;
+      }
+      next = [...routes.value, route];
+    }
+    await save(next);
+    editorOpen.value = false;
+    push("Routes saved");
+  } catch (err) {
+    push(`Save failed: ${err instanceof Error ? err.message : err}`, "bad");
+  } finally {
+    saving.value = false;
+  }
+}
+
+async function onToggle(route: Route): Promise<void> {
+  try {
+    await save(routes.value.map((r) => (r.id === route.id ? route : r)));
+  } catch (err) {
+    push(`Save failed: ${err instanceof Error ? err.message : err}`, "bad");
+    load();
+  }
+}
+
+async function onDelete(route: Route): Promise<void> {
+  if (!window.confirm(`Delete route "${route.name || route.id}"?`)) return;
+  try {
+    await save(routes.value.filter((r) => r.id !== route.id));
+    push("Route deleted");
+  } catch (err) {
+    push(`Delete failed: ${err instanceof Error ? err.message : err}`, "bad");
+  }
+}
+</script>