refactor: move project under backend

backend/x402/facilitator/tokens.json

@@ -0,0 +1,21 @@
+{
+  "evm": {
+    "ethereum": {
+      "USDC": { "address": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", "decimals": 6 },
+      "USDT": { "address": "0xdAC17F958D2ee523a2206206994597C13D831ec7", "decimals": 6 },
+      "ETH": { "native": true, "decimals": 18 }
+    },
+    "bsc": {
+      "USDC": { "address": "0x8ac76a51cc950d9822d68b83fe1ad97b32cd580d", "decimals": 18 },
+      "USDT": { "address": "0x55d398326f99059fF775485246999027B3197955", "decimals": 18 },
+      "BNB": { "native": true, "decimals": 18 }
+    }
+  },
+  "svm": {
+    "solana": {
+      "USDC": { "mint": "EPjFWdd5AufqSSqeM2qE1z3vY2Z9K5xkqkQ3yqC4wR5Z", "decimals": 6 },
+      "USDT": { "mint": "Es9vMFrzaCERzmxEtpmJieE5s3bD4ZjbFj9a2yq6VQ8G", "decimals": 6 },
+      "SOL": { "native": true, "decimals": 9 }
+    }
+  }
+}