feat(export): add sns stats card and conversation tab updates

src/types/electron.d.ts

@@ -539,6 +539,7 @@ export interface ElectronAPI {
     onExportProgress: (callback: (payload: { current: number; total: number; status: string }) => void) => () => void
     selectExportDir: () => Promise<{ canceled: boolean; filePath?: string }>
     getSnsUsernames: () => Promise<{ success: boolean; usernames?: string[]; error?: string }>
+    getExportStats: () => Promise<{ success: boolean; data?: { totalPosts: number; totalFriends: number }; error?: string }>
     installBlockDeleteTrigger: () => Promise<{ success: boolean; alreadyInstalled?: boolean; error?: string }>
     uninstallBlockDeleteTrigger: () => Promise<{ success: boolean; error?: string }>
     checkBlockDeleteTrigger: () => Promise<{ success: boolean; installed?: boolean; error?: string }>