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.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/web/src/stores/toasts.ts

@@ -0,0 +1,45 @@
+import { defineStore } from 'pinia';
+import { ref } from 'vue';
+
+export type ToastKind = 'success' | 'error' | 'info';
+
+export interface Toast {
+  id: number;
+  kind: ToastKind;
+  message: string;
+  timeout: number;
+}
+
+/** File de notifications éphémères. Aucun couplage : les vues appellent success/error/info. */
+export const useToastsStore = defineStore('toasts', () => {
+  const toasts = ref<Toast[]>([]);
+  let seq = 0;
+  const timers = new Map<number, ReturnType<typeof setTimeout>>();
+
+  function dismiss(id: number): void {
+    toasts.value = toasts.value.filter((t) => t.id !== id);
+    const timer = timers.get(id);
+    if (timer) {
+      clearTimeout(timer);
+      timers.delete(id);
+    }
+  }
+
+  function push(kind: ToastKind, message: string, timeout = 4000): number {
+    const id = ++seq;
+    toasts.value = [...toasts.value, { id, kind, message, timeout }];
+    if (timeout > 0) timers.set(id, setTimeout(() => dismiss(id), timeout));
+    return id;
+  }
+
+  const success = (message: string): number => push('success', message);
+  const info = (message: string): number => push('info', message);
+
+  /** Normalise n'importe quelle erreur (ApiError/Error/inconnu) en message lisible. Sticky par défaut. */
+  function error(err: unknown, timeout = 0): number {
+    const message = err instanceof Error ? err.message : String(err);
+    return push('error', message, timeout);
+  }
+
+  return { toasts, push, success, info, error, dismiss };
+});