feat: add web3-pay skill for crypto payments

skills/web3-pay/SKILL.md

@@ -0,0 +1,75 @@
+---
+name: web3-pay
+description: Accept crypto payments (USDC) on Base, Polygon, Ethereum, and Arbitrum. Verify on-chain transactions, manage paid users, and track subscriptions.
+---
+
+# Web3 Pay
+
+Accept cryptocurrency payments and manage user subscriptions through on-chain USDC transfers.
+
+## When to Use
+
+- User wants to pay for a service or subscription
+- Need to verify a crypto payment transaction
+- Managing paid user access (grant, check, revoke)
+- Checking recent transfers to a wallet
+
+## Setup
+
+Set environment variables:
+```bash
+export WEB3PAY_ADDRESS=0xYourWalletAddress
+export WEB3PAY_CHAIN=base  # base | polygon | ethereum | arbitrum
+export BASESCAN_API_KEY=your_key  # optional, for better rate limits
+```
+
+## Commands
+
+```bash
+# Show payment info (address, plans, chain)
+python3 web3pay.py info --address 0x... --chain base
+
+# Verify a transaction
+python3 web3pay.py verify --tx 0xTransactionHash --address 0x...
+
+# Get recent USDC transfers to address
+python3 web3pay.py transfers --address 0x...
+
+# Grant access to a user
+python3 web3pay.py grant --user user123 --plan monthly --tx 0x...
+
+# Check if user has access
+python3 web3pay.py check --user user123
+
+# Revoke access
+python3 web3pay.py revoke --user user123
+
+# List all paid users
+python3 web3pay.py list
+```
+
+## Payment Flow
+
+1. User requests to subscribe → Show wallet address + pricing
+2. User sends USDC on Base/Polygon/ETH → Gets transaction hash
+3. Verify transaction → `verify --tx 0x...` confirms the transfer
+4. Grant access → `grant --user X --plan monthly`
+
+## Supported Chains
+
+| Chain | Gas Cost | Best For |
+|-------|----------|----------|
+| Base | ~$0.01 | Recommended - cheapest |
+| Polygon | ~$0.01 | Alternative cheap option |
+| Arbitrum | ~$0.05 | Ethereum L2 |
+| Ethereum | $1-5 | High-value only |
+
+## Default Plans
+
+- `monthly`: 10 USDC (30 days)
+- `yearly`: 50 USDC (365 days)
+- `lifetime`: 100 USDC (forever)
+
+## Source
+
+https://github.com/BENZEMA216/clawdbot-skill-web3-pay