feat(web): router with auth guard, AppShell, login + home views

web/src/views/HomeView.vue

@@ -0,0 +1,14 @@
+<template>
+  <AppShell>
+    <div class="space-y-4">
+      <h2 class="text-xl font-semibold">欢迎，{{ auth.user?.display_name }}</h2>
+      <p>这是占位 dashboard。后续 plan 会接入项目/工作区/Issue。</p>
+    </div>
+  </AppShell>
+</template>
+
+<script setup lang="ts">
+import AppShell from '@/layouts/AppShell.vue'
+import { useAuthStore } from '@/stores/auth'
+const auth = useAuthStore()
+</script>