chore(agents): drop now-unused deps after removing dead x402/direct-pay demo code

@anthropic-ai/sdk (buyer-agent) and @solana/pay + bignumber.js (seller-agent)
had no remaining consumer after the prior commit's file deletions.

Author: trilltino

coral-agents/buyer-agent/package.json

@@ -12,7 +12,6 @@
   "dependencies": {
     "@pay/agent-runtime": "0.1.0",
     "@coral-xyz/anchor": "^0.32.1",
-    "@anthropic-ai/sdk": "^0.100.0",
     "@solana/web3.js": "^1.98.0"
   },
   "devDependencies": {

coral-agents/seller-agent/package.json

@@ -14,9 +14,7 @@
     "@pay/harness-runtime": "0.1.0",
     "@pay/payment-runtime": "0.1.0",
     "@coral-xyz/anchor": "^0.32.1",
-    "@solana/web3.js": "^1.98.0",
-    "@solana/pay": "^0.2.5",
-    "bignumber.js": "^9.1.2"
+    "@solana/web3.js": "^1.98.0"
   },
   "devDependencies": {
     "typescript": "^5.4.0",