Sell a Digital Product with LemonSqueezy

I want to sell a digital product using LemonSqueezy as my payment processor. Help me set up everything from product creation to delivery.

Product details:
- Product name: [e.g. "The Founder's Prompt Library", "SaaS UI Kit", "Video Course"]
- Product type: [e.g. downloadable file, license key, course access]
- Price: $[X] one-time (or $[X]/mo subscription)
- File to deliver: [e.g. "a ZIP file", "a PDF", "access to a members area"]
- My website: [URL where the buy button will live]
- Framework (if any): [e.g. Next.js, Astro, WordPress, or "just a landing page"]

Walk me through the complete setup:

1. LemonSqueezy store configuration:
   - Create my store and set the name, description, and branding
   - Add my payout details (bank or PayPal)
   - Set my store's currency and tax settings
   - Enable the LemonSqueezy tax-inclusive pricing (they handle global tax for me)

2. Product and variant creation:
   - Create the product with name, description, and cover image
   - Upload my deliverable file or set up license key generation
   - If subscription: set up the recurring billing interval
   - Add a variant if I want multiple tiers (e.g. Basic $29 / Pro $49)
   - Set up a discount code: [e.g. LAUNCH20 for 20% off]

3. Checkout integration on my website:
   - Option A (simplest): Use the LemonSqueezy overlay checkout
     Give me the exact HTML for a buy button that opens the checkout overlay:
     [script tag + button with data attributes]
   - Option B (custom): Use the API to create a checkout session
     Show me the fetch call to create a checkout URL server-side
   - Pass the customer's email if they're already logged in
   - Add URL parameters for affiliate tracking or UTM attribution

4. Post-purchase delivery:
   - Configure the automatic file delivery email
   - Set up a custom thank-you page redirect to [URL]
   - If selling license keys: show me how to validate a key via the API

5. Webhook setup (if I need to grant access in my app):
   - Set up a webhook endpoint for "order_created"
   - Verify the webhook signature
   - Parse the payload to get: customer email, product ID, order ID
   - Grant access in my app (e.g. flip a boolean in my database)
   - Give me the complete webhook handler code for [framework]

6. Sales dashboard essentials:
   - Where to see daily revenue and total customers
   - How to issue a refund
   - How to export customer emails for my newsletter

Keep it simple. I want to go from zero to accepting payments within an hour.