feat: bump typescript (#14507)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
  * Upgraded TypeScript toolchain to v5.9.3 across packages and tooling.
* Removed legacy ts-node and migrated developer tooling to newer
runtimes (tsx/SWC) where applicable.
* **Documentation**
* Updated developer CLI docs and runtime behavior notes to reflect the
new loader/runtime for running TypeScript files; no changes to public
APIs or end-user behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/package.json

@@ -96,9 +96,7 @@
     "is-mobile": "^5.0.0",
     "jose": "^6.1.3",
     "jsonwebtoken": "^9.0.3",
-    "keyv": "^5.2.2",
     "lodash-es": "^4.17.23",
-    "mixpanel": "^0.18.0",
     "mustache": "^4.2.0",
     "nanoid": "^5.1.6",
     "nest-commander": "^3.15.0",
@@ -136,7 +134,6 @@
     "@types/http-errors": "^2.0.4",
     "@types/jsonwebtoken": "^9.0.9",
     "@types/lodash-es": "^4.17.12",
-    "@types/mixpanel": "^2.14.9",
     "@types/mustache": "^4.2.5",
     "@types/node": "^22.0.0",
     "@types/nodemailer": "^7.0.0",
@@ -153,8 +150,7 @@
     "sinon": "^21.0.1",
     "socket.io-client": "^4.8.3",
     "supertest": "^7.1.4",
-    "ts-node": "^10.9.2",
-    "typescript": "^5.7.2",
+    "typescript": "^5.9.3",
     "why-is-node-running": "^3.2.2"
   },
   "nodemonConfig": {