chore: create upload directory when server starts

[rabi-siddique]

While testing the Causeway deployment on Kubernetes, I discovered that although the server starts successfully, file uploads consistently fail due to the upload directory not being created on time. To resolve this issue, I have adjusted the server's startup process to ensure the directory is created beforehand.

Here are the relevant Kubernetes logs:

kubectl logs causeway-prod-5d5694c76b-5ggb8
plantuml.jar not found. Downloading...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 9862k  100 9862k    0     0   935k      0  0:00:10  0:00:10 --:--:-- 1279k
Downloaded plantuml.jar successfully.
Running in production mode...
yarn run v1.22.22
$ node index.js
Server listening on 3000
Multiple 'POST /upload' requests resulted in 'ENOENT: no such file or directory' errors, indicating the absence of the required 'uploads' directory.

These logs were generated while addressing file upload failures, and the adjustments to directory creation should prevent further errors of this nature.