feat: Add demo account creation functionality

- Introduce a new DemoAccountCreator component for generating test accounts with auto-generated credentials.
- Implement useDemoAccountGenerator composable to handle credential generation and state management.
- Update routing to replace the existing login page with the new LoginDemo page for demo account access.
- Add unique-names-generator package to facilitate username generation.

src/components/demo/DemoAccountCreator.vue

@@ -0,0 +1,139 @@
+<template>
+  <div class="space-y-4">
+    <!-- Demo Mode Banner -->
+    <div class="bg-yellow-50 border border-yellow-200 rounded-lg p-4">
+      <div class="flex items-center gap-2">
+        <div class="w-2 h-2 bg-yellow-500 rounded-full animate-pulse"></div>
+        <p class="text-sm text-yellow-800 font-medium">
+          Demo Mode Active
+        </p>
+      </div>
+      <p class="text-xs text-yellow-700 mt-1">
+        This is a demo environment. Use the button below to create a test account.
+      </p>
+    </div>
+
+    <!-- Demo Account Creation -->
+    <Card>
+      <CardHeader>
+        <CardTitle class="text-lg">Quick Demo Account</CardTitle>
+        <CardDescription>
+          Create a test account with auto-generated credentials
+        </CardDescription>
+      </CardHeader>
+      <CardContent class="space-y-4">
+        <!-- Generated Credentials Display -->
+        <div v-if="generatedCredentials" class="space-y-3 p-3 bg-gray-50 rounded-lg">
+          <div class="space-y-2">
+            <Label class="text-sm font-medium text-gray-700">Username:</Label>
+            <div class="flex items-center gap-2">
+              <Input :value="generatedCredentials.username" readonly class="font-mono text-sm" />
+              <Button 
+                variant="outline" 
+                size="sm" 
+                @click="copyToClipboard(generatedCredentials.username)"
+                class="shrink-0"
+              >
+                Copy
+              </Button>
+            </div>
+          </div>
+          <div class="space-y-2">
+            <Label class="text-sm font-medium text-gray-700">Password:</Label>
+            <div class="flex items-center gap-2">
+              <Input :value="generatedCredentials.password" readonly class="font-mono text-sm" />
+              <Button 
+                variant="outline" 
+                size="sm" 
+                @click="copyToClipboard(generatedCredentials.password)"
+                class="shrink-0"
+              >
+                Copy
+              </Button>
+            </div>
+          </div>
+        </div>
+
+        <!-- Create Account Button -->
+        <Button 
+          @click="createFakeAccount" 
+          :disabled="isLoading" 
+          class="w-full"
+        >
+          <span v-if="isLoading" class="animate-spin mr-2">⚡</span>
+          {{ isLoading ? 'Creating Account...' : 'Create Demo Account' }}
+        </Button>
+
+        <!-- Error Display -->
+        <p v-if="error" class="text-sm text-destructive text-center">
+          {{ error }}
+        </p>
+
+        <!-- Success Message -->
+        <div v-if="successMessage" class="text-sm text-green-600 text-center bg-green-50 p-3 rounded-lg">
+          {{ successMessage }}
+        </div>
+      </CardContent>
+    </Card>
+  </div>
+</template>
+
+<script setup lang="ts">
+import { ref } from 'vue'
+import { useRouter } from 'vue-router'
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
+import { Button } from '@/components/ui/button'
+import { Input } from '@/components/ui/input'
+import { Label } from '@/components/ui/label'
+import { auth } from '@/composables/useAuth'
+import { useDemoAccountGenerator } from '@/composables/useDemoAccountGenerator'
+import { toast } from 'vue-sonner'
+
+const router = useRouter()
+const { isLoading, error, generatedCredentials, generateNewCredentials } = useDemoAccountGenerator()
+const successMessage = ref('')
+
+// Copy text to clipboard
+async function copyToClipboard(text: string) {
+  try {
+    await navigator.clipboard.writeText(text)
+    toast.success('Copied to clipboard!')
+  } catch (err) {
+    toast.error('Failed to copy to clipboard')
+  }
+}
+
+// Create fake account and automatically log in
+async function createFakeAccount() {
+  try {
+    isLoading.value = true
+    error.value = ''
+    successMessage.value = ''
+
+    // Generate credentials
+    const credentials = generateNewCredentials()
+
+    // Register the fake account
+    await auth.register({
+      username: credentials.username,
+      email: credentials.email,
+      password: credentials.password,
+      password_repeat: credentials.password
+    })
+
+    successMessage.value = 'Account created successfully! Logging you in...'
+    toast.success('Demo account created and logged in!')
+
+    // Redirect to home page after successful registration
+    setTimeout(() => {
+      router.push('/')
+    }, 1500)
+
+  } catch (err) {
+    error.value = err instanceof Error ? err.message : 'Failed to create demo account'
+    toast.error('Failed to create demo account. Please try again.')
+  } finally {
+    isLoading.value = false
+  }
+}
+</script>