feat: add toast notification system

src/App.vue

@@ -1,38 +1,18 @@
 <script setup lang="ts">
-// Main App component - layout placeholder
+import TitleBar from './components/TitleBar.vue'
+import NavRail from './components/NavRail.vue'
+import ToastNotification from './components/ToastNotification.vue'
 </script>
 
 <template>
-  <div class="h-full w-full flex flex-col bg-background">
-    <!-- TitleBar placeholder -->
-    <header class="h-10 flex items-center justify-between px-4 bg-surface border-b border-border" data-tauri-drag-region>
-      <div class="flex items-center gap-2">
-        <span class="text-amber font-semibold">ZeroClock</span>
-      </div>
-      <div class="flex items-center gap-2">
-        <!-- Window controls would go here -->
-      </div>
-    </header>
-
-    <!-- TimerBar placeholder -->
-    <div class="h-16 flex items-center justify-center bg-surface border-b border-border">
-      <span class="text-text-secondary">Timer Bar Placeholder</span>
-    </div>
-
-    <!-- Main content area -->
+  <div class="h-full w-full flex flex-col bg-bg-base">
+    <TitleBar />
     <div class="flex-1 flex overflow-hidden">
-      <!-- Sidebar placeholder -->
-      <aside class="w-16 flex flex-col items-center py-4 bg-surface border-r border-border">
-        <div class="text-text-secondary text-sm">Sidebar</div>
-      </aside>
-
-      <!-- Main content -->
-      <main class="flex-1 p-6 overflow-auto">
+      <NavRail />
+      <main class="flex-1 overflow-auto">
         <router-view />
       </main>
     </div>
   </div>
+  <ToastNotification />
 </template>
-
-<style scoped>
-</style>

src/components/ToastNotification.vue

@@ -0,0 +1,28 @@
+<script setup lang="ts">
+import { useToastStore } from '../stores/toast'
+import { Check, AlertCircle, Info } from 'lucide-vue-next'
+
+const toastStore = useToastStore()
+</script>
+
+<template>
+  <div class="fixed top-4 left-1/2 -translate-x-1/2 z-[100] flex flex-col gap-2 pointer-events-none" style="margin-left: 24px;">
+    <div
+      v-for="toast in toastStore.toasts"
+      :key="toast.id"
+      @click="toastStore.removeToast(toast.id)"
+      class="w-80 flex items-center gap-3 px-4 py-3 bg-bg-surface border border-border-subtle rounded shadow-lg cursor-pointer pointer-events-auto border-l-[3px]"
+      :class="[
+        toast.exiting ? 'animate-toast-exit' : 'animate-toast-enter',
+        toast.type === 'success' ? 'border-l-status-running' : '',
+        toast.type === 'error' ? 'border-l-status-error' : '',
+        toast.type === 'info' ? 'border-l-accent' : ''
+      ]"
+    >
+      <Check v-if="toast.type === 'success'" class="w-4 h-4 text-status-running shrink-0" :stroke-width="2" />
+      <AlertCircle v-if="toast.type === 'error'" class="w-4 h-4 text-status-error shrink-0" :stroke-width="2" />
+      <Info v-if="toast.type === 'info'" class="w-4 h-4 text-accent shrink-0" :stroke-width="2" />
+      <span class="text-sm text-text-primary">{{ toast.message }}</span>
+    </div>
+  </div>
+</template>

src/stores/toast.ts

@@ -0,0 +1,43 @@
+import { defineStore } from 'pinia'
+import { ref } from 'vue'
+
+export interface Toast {
+  id: number
+  message: string
+  type: 'success' | 'error' | 'info'
+  exiting?: boolean
+}
+
+export const useToastStore = defineStore('toast', () => {
+  const toasts = ref<Toast[]>([])
+  let nextId = 0
+
+  function addToast(message: string, type: Toast['type'] = 'info') {
+    const id = nextId++
+    toasts.value.push({ id, message, type })
+
+    // Max 3 visible
+    if (toasts.value.length > 3) {
+      toasts.value.shift()
+    }
+
+    // Auto-dismiss after 3s
+    setTimeout(() => removeToast(id), 3000)
+  }
+
+  function removeToast(id: number) {
+    const toast = toasts.value.find(t => t.id === id)
+    if (toast) {
+      toast.exiting = true
+      setTimeout(() => {
+        toasts.value = toasts.value.filter(t => t.id !== id)
+      }, 150)
+    }
+  }
+
+  function success(message: string) { addToast(message, 'success') }
+  function error(message: string) { addToast(message, 'error') }
+  function info(message: string) { addToast(message, 'info') }
+
+  return { toasts, addToast, removeToast, success, error, info }
+})