Add createdByUsername field and boot-time admin seed/backfill

Adds AdminTransaction.createdByUsername (default null) so future
permission-scoped views can attribute data to a user, plus a new
app/libs/adminBootstrap.js that seeds the first admin account from
ADMIN_USER/ADMIN_PASSWORD on boot and backfills any pre-existing
transaction lacking createdByUsername to that admin. Wired into
server.js's mongoose 'open' handler. Idempotent across repeated boots.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/libs/adminBootstrap.js

+"use strict";
+var AdminUser = require("../models/AdminUser");
+var AdminTransaction = require("../models/AdminTransaction");
+var passwordHash = require("./passwordHash");
+
+module.exports = function run(config, callback) {
+  AdminUser.findOne({ role: "admin" }, function (err, existingAdmin) {
+    if (err) {
+      return callback(err);
+    }
+    if (existingAdmin) {
+      return backfillTransactions(existingAdmin.username, callback);
+    }
+    if (!config.admin || !config.admin.user || !config.admin.password) {
+      console.error("adminBootstrap: no admin exists and ADMIN_USER/ADMIN_PASSWORD not set - cannot seed");
+      return callback(null);
+    }
+    AdminUser.create(
+      {
+        username: String(config.admin.user).trim().toLowerCase(),
+        passwordHash: passwordHash.hash(config.admin.password),
+        role: "admin",
+        active: true,
+      },
+      function (createErr, admin) {
+        if (createErr) {
+          return callback(createErr);
+        }
+        console.log("adminBootstrap: seeded first admin account:", admin.username);
+        return backfillTransactions(admin.username, callback);
+      }
+    );
+  });
+};
+
+function backfillTransactions(adminUsername, callback) {
+  AdminTransaction.updateMany(
+    { createdByUsername: null },
+    { createdByUsername: adminUsername },
+    function (err, result) {
+      if (err) {
+        return callback(err);
+      }
+      if (result && result.nModified) {
+        console.log("adminBootstrap: backfilled", result.nModified, "old transactions to", adminUsername);
+      }
+      return callback(null);
+    }
+  );
+}

app/models/AdminTransaction.js

@@ -19,6 +19,7 @@ var AdminTransactionSchema = new Schema(
     merchantToken: { type: String, required: true },
     timeStamp: { type: String, required: true },
     resultMsg: { type: String, default: "" },
+    createdByUsername: { type: String, default: null },
     paidAt: { type: Date, default: null },
   },
   { timestamps: true }

server.js

@@ -25,6 +25,11 @@ mongoose.connection.on('error', function (err) {
 });
 mongoose.connection.once('open', function () {
     console.log('MongoDB connected');
+    require('./app/libs/adminBootstrap')(config, function (err) {
+        if (err) {
+            console.error('adminBootstrap failed:', err.message);
+        }
+    });
 });
 
 /**