fix(auth): always regenerate cookies.txt from auth.json, don't skip if yt-dlp overwrote it

Previously cookies.txt was only regenerated when auth.json was newer. But yt-dlp
overwrites cookies.txt during extraction with its own header ('generated by yt-dlp')
and potentially fewer/different cookies, losing the sessionid from auth.json.

Fix: remove mtime comparison — always regenerate cookies.txt from auth.json on each
extraction call. This ensures the full session cookie set is always present.
Also remove the now-unused statSync import.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/lib/server/instagram-extractor.ts

@@ -9,7 +9,7 @@
 
 import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
-import { existsSync, readFileSync, writeFileSync, statSync } from 'node:fs';
+import { existsSync, readFileSync, writeFileSync } from 'node:fs';
 import { logError } from './utils/logger';
 import type { ExtractedContent, ProgressCallback } from './extraction';
 
@@ -40,11 +40,7 @@ function maybeConvertAuthJson(): void {
 		const cookiePath = COOKIE_PATHS[i];
 		if (!existsSync(authPath)) continue;
 
-		// Re-generate whenever auth.json is newer than the existing cookies.txt
-		const authMtime = statSync(authPath).mtimeMs;
-		const cookieMtime = existsSync(cookiePath) ? statSync(cookiePath).mtimeMs : 0;
-		if (cookieMtime >= authMtime) continue;
-
+		// Always regenerate from auth.json so yt-dlp cannot overwrite our session cookies
 		try {
 			const auth = JSON.parse(readFileSync(authPath, 'utf8')) as {
 				cookies?: PlaywrightCookie[];