feat(apps): add to nixFastBuild and clean up nix code

apps/update-sources/src/lib.ts

@@ -0,0 +1,30 @@
+import { spawnSync } from 'node:child_process';
+
+
+export const parseArgs = () => {
+    const args = {} as Record<string, unknown>;
+    let lastFlag: string | null = null;
+
+    for (let i = 2; i < process.argv.length; ++i) {
+        const arg = process.argv[i];
+
+        if (arg.toString().startsWith('-')) {
+            lastFlag = arg.toString().replace(/^-{1,2}/, '');
+            args[lastFlag] = true;
+        }
+        else if (lastFlag) {
+            args[lastFlag] = arg;
+            lastFlag = null;
+        }
+        else {
+            console.error(`Could not parse args: ${arg.toString()}`);
+        }
+    }
+
+    return args;
+};
+
+export const parseFetchurl = (url: string) => JSON.parse(spawnSync(
+    'nix', ['store', 'prefetch-file', '--refresh', '--json',
+        '--hash-type', 'sha256', url, '--name', '"escaped"'], { shell: true },
+).stdout.toString()).hash;