feat: add reusable PasswordInput with show/hide toggle

Replaces all type="password" inputs site-wide with a PasswordInput
component that includes an eye icon toggle for visibility.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/LoginPage.tsx

@@ -2,6 +2,7 @@ import { useState } from 'react'
 import { Link, useNavigate, useLocation } from 'react-router-dom'
 import { useAuthStore } from '@/store/authStore'
 import { BrandLogo } from '@/components/common/BrandLogo'
+import { PasswordInput } from '@/components/common/PasswordInput'
 import { cn } from '@/lib/utils'
 
 export function LoginPage() {
@@ -95,10 +96,9 @@ export function LoginPage() {
               <label htmlFor="password" className="mb-1 block text-sm font-medium text-white">
                 Password
               </label>
-              <input
+              <PasswordInput
                 id="password"
                 name="password"
-                type="password"
                 autoComplete="current-password"
                 required
                 value={password}