refactor[epic-games]: migrate to GraphQL API and modularize authentication logic

This commit refactors epic-games.js to use the GraphQL API instead of the legacy promotions endpoint for retrieving free games. Key architectural improvements include:

- Added modular authentication module (device-auths.ts) supporting persistent device auth tokens
- Introduces cookie management module (cookie.ts) for persistent session handling
- Extracts GraphQL query structures and API endpoints into constants.ts
- Implements multiple fallback strategies: device auth login, token exchange, and fallback to standard login
- Adds support for both GraphQL and promotions-based game discovery
- Streamlines claim process with improved tracking and error handling
- Removes legacy selectors and redundant logic

Additionally, updates package.json to include TypeScript and reorganizes dependency order for better maintainability.

src/device-auths.ts

@@ -0,0 +1,38 @@
+// Device authentication management for Epic Games
+// Based on https://github.com/claabs/epicgames-freegames-node
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { dataDir } from './util.js';
+
+const CONFIG_DIR = dataDir('config');
+const deviceAuthsFilename = path.join(CONFIG_DIR, 'device-auths.json');
+
+// Ensure config directory exists
+if (!fs.existsSync(CONFIG_DIR)) {
+  fs.mkdirSync(CONFIG_DIR, { recursive: true });
+}
+
+export async function getDeviceAuths() {
+  try {
+    const deviceAuths = JSON.parse(fs.readFileSync(deviceAuthsFilename, 'utf-8'));
+    return deviceAuths;
+  } catch {
+    return undefined;
+  }
+}
+
+export async function getAccountAuth(account) {
+  const deviceAuths = await getDeviceAuths();
+  return deviceAuths?.[account];
+}
+
+export async function writeDeviceAuths(deviceAuths) {
+  fs.writeFileSync(deviceAuthsFilename, JSON.stringify(deviceAuths, null, 2));
+}
+
+export async function setAccountAuth(account, accountAuth) {
+  const existingDeviceAuths = (await getDeviceAuths()) ?? {};
+  existingDeviceAuths[account] = accountAuth;
+  await writeDeviceAuths(existingDeviceAuths);
+}