feat: css editor (#1542)

* feat: allow editing CSS from settings

---------

Co-authored-by: Carlos Valente <carlosvalente@pm.me>

refactor: style tweaks

apps/server/src/api-data/assets/assets.service.ts

@@ -0,0 +1,33 @@
+import { publicFiles } from '../../setup/index.js';
+import { existsSync } from 'node:fs';
+import { readFile, writeFile } from 'node:fs/promises';
+import { defaultCss } from '../../user/styles/bundledCss.js';
+
+/**
+ * Reads the user's css file
+ * @returns css contents in the file
+ */
+export async function readCssFile(): Promise<string> {
+  const path = publicFiles.cssOverride;
+  if (!existsSync(path)) {
+    await writeFile(path, defaultCss, { encoding: 'utf8' });
+  }
+
+  const css = await readFile(path, { encoding: 'utf8' });
+
+  return css;
+}
+
+/**
+ * Writes the user's css file
+ * @param css the updated css to write to file
+ */
+export async function writeCssFile(css: string) {
+  const path = publicFiles.cssOverride;
+  if (!existsSync(path)) {
+    await writeFile(path, css, { encoding: 'utf8' });
+    return;
+  }
+
+  await writeFile(path, css, { encoding: 'utf8' });
+}