feat: refonte UX du dashboard (coquille, tri/filtre/pagination, ⌘K, toasts)

Refonte front (packages/web) : coquille applicative partagée (sidebar desktop +
barre d'onglets mobile + PageHeader, langue/push/logout centralisés) pilotée par
route.meta.layout ; design system (BaseButton/BaseBadge/SegmentedControl/EmptyState/
SkeletonRow, anneau de focus, icônes @lucide/vue) ; tri/filtre/recherche/pagination
côté client via useListControls (+ synchro URL) sur sessions/worktrees/groupes ;
section « À traiter », palette de commandes ⌘K, toasts. Aucune modif serveur/protocole/DB.

packages/web/src/components/layout/AppShellFooter.vue

@@ -0,0 +1,57 @@
+<template>
+  <div class="flex flex-col gap-2">
+    <p v-if="pushErrorText" class="text-xs text-amber-400">{{ pushErrorText }}</p>
+    <div class="flex items-center gap-2">
+      <LanguageSwitcher />
+      <BaseButton
+        v-if="push.supported"
+        variant="ghost"
+        size="sm"
+        icon-only
+        :icon="push.enabled ? Bell : BellOff"
+        :class="push.enabled ? 'text-emerald-300' : ''"
+        :disabled="push.busy"
+        :title="pushErrorText || undefined"
+        :aria-label="push.enabled ? t('push.disable') : t('push.enable')"
+        @click="push.toggle()"
+      />
+      <BaseButton
+        variant="ghost"
+        size="sm"
+        icon-only
+        :icon="LogOut"
+        class="ml-auto"
+        :aria-label="t('common.logout')"
+        @click="logout"
+      />
+    </div>
+    <span v-if="auth.serverVersion" class="text-[11px] text-zinc-600">v{{ auth.serverVersion }}</span>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { computed, onMounted } from 'vue';
+import { useI18n } from 'vue-i18n';
+import { Bell, BellOff, LogOut } from '@lucide/vue';
+import { useAuthStore } from '../../stores/auth';
+import { usePushStore } from '../../stores/push';
+import { useSession } from '../../composables/useSession';
+import BaseButton from '../ui/BaseButton.vue';
+import LanguageSwitcher from '../LanguageSwitcher.vue';
+
+const { t } = useI18n();
+const auth = useAuthStore();
+const push = usePushStore();
+const { logout } = useSession();
+
+// 'denied'/'unsupported' sont des clés i18n ; tout autre message d'erreur est affiché tel quel.
+const pushErrorText = computed(() => {
+  const e = push.error;
+  if (!e) return '';
+  return e === 'denied' || e === 'unsupported' ? t(`push.${e}`) : e;
+});
+
+onMounted(() => {
+  void push.refresh();
+});
+</script>