Add Mega-Debrid account info check (web scraping)

Scrapes the Mega-Debrid profile page to display username, premium status,
remaining days, and loyalty points. New "Account prüfen" button in Settings > Accounts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/preload/preload.ts

@@ -4,6 +4,7 @@ import {
   AppSettings,
   DuplicatePolicy,
   HistoryEntry,
+  ProviderAccountInfo,
   SessionStats,
   StartConflictEntry,
   StartConflictResolutionResult,
@@ -53,6 +54,7 @@ const api: ElectronApi = {
   getHistory: (): Promise<HistoryEntry[]> => ipcRenderer.invoke(IPC_CHANNELS.GET_HISTORY),
   clearHistory: (): Promise<void> => ipcRenderer.invoke(IPC_CHANNELS.CLEAR_HISTORY),
   removeHistoryEntry: (entryId: string): Promise<void> => ipcRenderer.invoke(IPC_CHANNELS.REMOVE_HISTORY_ENTRY, entryId),
+  checkAccount: (provider: string): Promise<ProviderAccountInfo> => ipcRenderer.invoke(IPC_CHANNELS.CHECK_ACCOUNT, provider),
   onStateUpdate: (callback: (snapshot: UiSnapshot) => void): (() => void) => {
     const listener = (_event: unknown, snapshot: UiSnapshot): void => callback(snapshot);
     ipcRenderer.on(IPC_CHANNELS.STATE_UPDATE, listener);