I need a clean, lightweight code snippet that adds a fully functional custom form to my existing WordPress site. The form should sit inside a page I specify (or be insertable via a shortcode), validate user input on the client and server sides, save each submission in the WordPress database, and trigger a notification email to an address I can change later from the admin panel. No bulky plugins, just straightforward PHP + HTML + minimal CSS that plays nicely with my current theme. Please keep the code well-commented so I can tweak field labels or add new ones without hunting around. Also include a quick read-me explaining where each file or function belongs and how to re-use the form on additional pages. Deliverables: • Fully tested form code (functions.php snippet or small custom plugin) • Any supporting CSS/JS files, namespaced to avoid conflicts • Brief setup instructions and notes on where to modify fields, email recipient, and success message If you can turn this around quickly and keep everything lightweight, let’s get started.