feat: add PasswordStrength component with real-time strength scoring

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/components/register/PasswordStrength.vue

@@ -0,0 +1,53 @@
+<script setup lang="ts">
+const props = defineProps<{ password: string }>()
+
+const score = computed(() => {
+  const p = props.password
+  if (!p) return 0
+
+  let s = 0
+  const hasLower = /[a-z]/.test(p)
+  const hasUpper = /[A-Z]/.test(p)
+  const hasDigit = /\d/.test(p)
+  const hasSpecial = /[^a-zA-Z\d]/.test(p)
+
+  if (p.length >= 8 && hasLower && hasDigit) s = 2
+  if (p.length >= 10 && hasLower && hasUpper && hasDigit) s = 3
+  if (p.length >= 12 && hasLower && hasUpper && hasDigit && hasSpecial) s = 4
+  // Fallback: any input < 8 or single-type = weak
+  if (s === 0 && p.length > 0) s = 1
+
+  return s
+})
+
+const label = computed(() => {
+  const labels = ['', '弱', '中', '强', '很强']
+  return labels[score.value]
+})
+
+const barWidth = computed(() => `${(score.value / 4) * 100}%`)
+
+const barColor = computed(() => {
+  const colors = ['', 'bg-red-500', 'bg-amber-500', 'bg-green-500', 'bg-emerald-500']
+  return colors[score.value]
+})
+</script>
+
+<template>
+  <div v-if="score > 0" class="mt-1 space-y-1">
+    <div class="h-1 w-full rounded-full bg-(--ui-bg-accented)">
+      <div
+        data-testid="strength-bar"
+        :data-score="score"
+        :class="[barColor, 'h-1 rounded-full transition-all duration-300']"
+        :style="{ width: barWidth }"
+      />
+    </div>
+    <p class="text-xs" :class="{
+      'text-red-500': score === 1,
+      'text-amber-500': score === 2,
+      'text-green-500': score === 3,
+      'text-emerald-500': score === 4,
+    }">{{ label }}</p>
+  </div>
+</template>

app/components/register/__tests__/PasswordStrength.test.ts

@@ -0,0 +1,39 @@
+import { describe, it, expect } from 'vitest'
+import { mount } from '@vue/test-utils'
+import PasswordStrength from '../PasswordStrength.vue'
+
+describe('PasswordStrength', () => {
+  it('renders nothing for empty password', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: '' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').exists()).toBe(false)
+  })
+
+  it('score 1 for weak password (only letters, < 8)', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: 'abc' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').attributes('data-score')).toBe('1')
+    expect(wrapper.text()).toContain('弱')
+  })
+
+  it('score 1 for only digits', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: '1234567' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').attributes('data-score')).toBe('1')
+  })
+
+  it('score 2 for letters+digits >= 8 chars', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: 'abc12345' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').attributes('data-score')).toBe('2')
+    expect(wrapper.text()).toContain('中')
+  })
+
+  it('score 3 for upper+lower+digits >= 10 chars', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: 'Abcdef1234' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').attributes('data-score')).toBe('3')
+    expect(wrapper.text()).toContain('强')
+  })
+
+  it('score 4 for upper+lower+digits+special >= 12 chars', () => {
+    const wrapper = mount(PasswordStrength, { props: { password: 'Abcdef1234!@' } })
+    expect(wrapper.find('[data-testid="strength-bar"]').attributes('data-score')).toBe('4')
+    expect(wrapper.text()).toContain('很强')
+  })
+})