build(deps): bump @stellar/stellar-sdk from 15.1.0 to 16.0.1

Bumps [@stellar/stellar-sdk](https://github.com/stellar/js-stellar-sdk) from 15.1.0 to 16.0.1.
- [Release notes](https://github.com/stellar/js-stellar-sdk/releases)
- [Changelog](https://github.com/stellar/js-stellar-sdk/blob/master/CHANGELOG.md)
- [Commits](stellar/js-stellar-sdk@v15.1.0...v16.0.1)

---
updated-dependencies:
- dependency-name: "@stellar/stellar-sdk"
  dependency-version: 16.0.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

backend/package.json

@@ -25,7 +25,7 @@
   "dependencies": {
     "@prisma/adapter-pg": "^7.8.0",
     "@prisma/client": "^7.8.0",
-    "@stellar/stellar-sdk": "^15.1.0",
+    "@stellar/stellar-sdk": "^16.0.1",
     "cors": "^2.8.6",
     "dotenv": "^17.4.2",
     "express": "^5.2.1",

frontend/package.json

@@ -13,7 +13,7 @@
   },
   "dependencies": {
     "@stellar/freighter-api": "^6.0.1",
-    "@stellar/stellar-sdk": "^15.1.0",
+    "@stellar/stellar-sdk": "^16.0.1",
     "@tanstack/react-query": "^5.101.0",
     "lucide-react": "^0.575.0",
     "next": "16.2.9",