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/components/procedural/IntakeFormModal.tsx

@@ -1,5 +1,6 @@
 import { useState } from 'react'
 import type { IntakeFormField } from '@/types'
+import { PasswordInput } from '@/components/common/PasswordInput'
 import { cn } from '@/lib/utils'
 
 interface IntakeFormModalProps {
@@ -119,8 +120,7 @@ export function IntakeFormModal({ isOpen, fields, treeName, onSubmit, onCancel }
 
       case 'password':
         input = (
-          <input
-            type="password"
+          <PasswordInput
             value={value}
             onChange={(e) => setValue(field.variable_name, e.target.value)}
             placeholder={field.placeholder}