Solana Mainnet Token Generator Upgrade

I already have a small HTML + JavaScript page that lets a user paste it into any browser (or a Web3-enabled one) to create a new SPL token on Solana devnet. I now need the exact same flow to run on mainnet.

What has to change
• Replace the current devnet connection with a mainnet endpoint, updating any web3.js calls so they point to mainnet-beta.
• Integrate Phantom Wallet so that the user first authorises and signs a payment (in SOL) before the token-creation transaction is sent. After the payment confirmation, the script should immediately mint the token and show the resulting token address back to the user.
• No new UX or design changes are required and no extra features such as minting limits or custom metadata—just replicate the current behaviour one-for-one on mainnet with the added payment step.

Deliverables
1. A single self-contained HTML/JS file (or minimal bundle) that:
– connects to mainnet-beta via @solana/web3.js
– prompts Phantom for payment, then mints the token once payment is approved
– returns the new token’s public address to the page
2. Brief notes explaining any environment variables or public keys I need to set before deploying.

I will provide the existing devnet code for reference, so you’ll only be adjusting the network targets, adding the Phantom payment flow, and making sure everything signs correctly on mainnet.