🔨 Run once, graceful shutdown, db filename in env

- Refactored toISODateString function
- Added Db filename to env
- Added getOrDefault function for fetching envs, replaced LOG_LEVEL with getOrDefault
- Added script to run job once then exit
- Catch SIGINT signal and do a graceful shutdown

package.json

@@ -5,6 +5,7 @@
   "main": "index.js",
   "scripts": {
     "start": "dotenvx run --env-file=.env.local -- node --import=tsx ./src/main.ts | pino-pretty",
+    "start-once": "ONCE=true dotenvx run --env-file=.env.local -- node --import=tsx ./src/main.ts | pino-pretty",
     "test": "dotenvx run --env-file=.env.test.local -- node --experimental-vm-modules node_modules/jest/bin/jest.js | pino-pretty",
     "format": "prettier --write \"./**/*.{js,mjs,ts,md,json}\""
   },