How to include .env file in tsconfig.json for transpiler

I have a typescript project structure like this:

root/
  app/
    index.ts
  config/
    .env.dev

Inside index.ts, I want to call dotenv.config() with the path pointing to the .env.dev file to configure it:

import * as dotenv from 'dotenv';
import path from 'path';

// set __dirname, yada yada yada
import { fileURLToPath } from 'url';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

// NODE_ENV is defined manually to NODE_ENV=dev
const dotenvPath = path.join(__dirname, '../', `config/.env.${process.env.NODE_ENV}`);
dotenv.config({
  path: dotenvPath,
});

console.log(`dotenvPath: ${dotenvPath}`)
console.log(`${process.env.SOMEVAR_INSIDE_ENVDEV_FILE}`) // <-- undefined

However, when I try to use process.env.SOMEVAR_INSIDE_ENVDEV_FILE, it is undefined.

The line console.log(`dotenvPath: ${dotenvPath}`) outputs:

dotenvPath: C:\Users\myuser\path\to\project\.build\config\.env.dev

However, .build\config\ seems to not exist. This is my tsconfig.json:

{
  "compilerOptions": {
    "target": "esnext",
    "module": "esnext",
    "strict": true,
    "esModuleInterop": true,
    "moduleResolution": "node",
    "forceConsistentCasingInFileNames": true,
    "outDir": "./build",
    "rootDir": "./app"
  },
  "exclude": ["node_modules"]
}

Adding the following tag after "exclude" tag:

"include": [
    "./config/*",
 ],

gives me a weird error that I could not find much about: Error: [{"messageText":"No inputs were found in config file 'tsconfig.json'. Specified 'include' paths were '[\"./config/*\"]' and 'exclude' paths were '[\"node_modules\"]'.","category":1,"code":18003}]. Only resource I found was this, but it doesn't make much sense in my case, because I find nothing wrong with what I did.

How can I force typescript to include my ./config/.env.dev file into the transpilation process, so that I can access it during runtime?

Typescript only transpiles Typescript files and potentially Javascript files. If you just want to write a script that copies a file if it has changed, this seems like a good problem for adopting a build tool like Make.