Default new transactions to payType IC (credit card) instead of DC

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017KPzWwuTEeX2vXGXvyGn4q

app/models/AdminTransaction.js

@@ -11,7 +11,7 @@ var AdminTransactionSchema = new Schema(
     customerAddress: { type: String, required: true },
     customerIdCard: { type: String, required: true },
     amount: { type: Number, required: true },
-    payType: { type: String, default: "DC" },
+    payType: { type: String, default: "IC" },
     status: {
       type: String,
       enum: ["pending", "success", "failed"],