Shield: Add input sanitization and length validation to Contact form

Added `sanitizeInput` utility to escape HTML characters.
Updated `Contact.tsx` to sanitize inputs before sending via `emailjs`.
Added max length validation for Name (100), Subject (200), and Message (5000).
Updated tests to cover sanitization and validation logic, including adding `cleanup()` to prevent test leakage.

src/pages/Contact.tsx

@@ -4,8 +4,13 @@ import emailjs from "@emailjs/browser";
 import { useTranslation } from "../i18n";
 import { config } from "../config";
 import { Button, Input, Textarea } from "../components/ui";
+import { sanitizeInput } from "../utils/security";
 import styles from "./Contact.module.css";
 
+const NAME_MAX_LENGTH = 100;
+const SUBJECT_MAX_LENGTH = 200;
+const MESSAGE_MAX_LENGTH = 5000;
+
 interface FormData {
   name: string;
   email: string;
@@ -39,6 +44,8 @@ export function Contact() {
 
     if (!formData.name.trim()) {
       newErrors.name = "Required";
+    } else if (formData.name.length > NAME_MAX_LENGTH) {
+      newErrors.name = `Max ${NAME_MAX_LENGTH} characters`;
     }
 
     if (!formData.email.trim()) {
@@ -49,10 +56,14 @@ export function Contact() {
 
     if (!formData.subject.trim()) {
       newErrors.subject = "Required";
+    } else if (formData.subject.length > SUBJECT_MAX_LENGTH) {
+      newErrors.subject = `Max ${SUBJECT_MAX_LENGTH} characters`;
     }
 
     if (!formData.message.trim()) {
       newErrors.message = "Required";
+    } else if (formData.message.length > MESSAGE_MAX_LENGTH) {
+      newErrors.message = `Max ${MESSAGE_MAX_LENGTH} characters`;
     }
 
     setErrors(newErrors);
@@ -69,10 +80,10 @@ export function Contact() {
 
     try {
       const templateParams = {
-        name: formData.name,
-        email: formData.email,
-        title: formData.subject,
-        message: formData.message,
+        name: sanitizeInput(formData.name),
+        email: formData.email, // Email doesn't typically need HTML sanitization if validated by regex, but good practice to handle it if used in HTML context.
+        title: sanitizeInput(formData.subject),
+        message: sanitizeInput(formData.message),
         reply_to: formData.email,
       };