fix(crypto): SHA-256 hash ENCRYPTION_KEY for AES-256-GCM

ENCRYPTION_KEY was 64 hex chars = 64 bytes. AES-256 needs exactly
32 bytes. Now hashing with SHA-256 to derive proper 32-byte key
regardless of input length. Fixed in auth.ts backfill encrypt
and wallet.ts encrypt/decrypt.

backend/src/routes/auth.ts

@@ -13,15 +13,12 @@ const TAUTULLI_API_KEY = process.env.TAUTULLI_API_KEY || "";
 
 function encrypt(text: string): string {
 	const iv = crypto.randomBytes(16);
-	const cipher = crypto.createCipheriv(
-		"aes-256-gcm",
-		Buffer.from(ENCRYPTION_KEY),
-		iv,
-	);
+	const key = crypto.createHash("sha256").update(ENCRYPTION_KEY).digest();
+	const cipher = crypto.createCipheriv("aes-256-gcm", key, iv);
 	let encrypted = cipher.update(text, "utf8", "hex");
 	encrypted += cipher.final("hex");
 	const authTag = cipher.getAuthTag();
-	return iv.toString("hex") + ":" + authTag.toString("hex") + ":" + encrypted;
+	return `${iv.toString("hex")}:${authTag.toString("hex")}:${encrypted}`;
 }
 
 const router = Router();