✨ Enhancement: Add batch export with progress tracking for multiple recordings

先阅读 apps/desktop 中现有的导出功能和 crates/recording 中的 Rust 编码器管线，然后跟踪当前的 TypeScript–Rust 视频导出入口点。将提议的队列、进度、重试、持久化和暂停/恢复行为与验收标准进行比较；完成意味着所有列出的批处理行为都能正常工作，同时 UI 保持响应。

🎯 Overview

This enhancement introduces the ability to export multiple recordings in batch with real-time progress tracking, pause/resume capabilities, and smart queue management.

🤔 Problem

Currently, users can only export recordings one at a time. For content creators, teams, and power users working with multiple recordings, this becomes tedious and time-consuming, especially when dealing with large files or slow network conditions.

✅ Solution

Implement a batch export system with:

Core Features

• 📦 Bulk Selection: Select multiple recordings from library and queue them for export
• ⏳ Progress Tracking: Real-time progress bar showing:
  • Current file being exported
  • Overall progress across all queued items
  • Estimated time remaining
  • Upload/download speed indicator
• ⏸️ Queue Management:
  • Pause/resume entire batch or individual items
  • Reorder queue items
  • Cancel specific exports without affecting others
• ⚙️ Export Presets: Save and apply custom export settings (format, quality, audio settings) to batch operations
• 🔔 Notifications: Completion alerts with summary (total files, duration, file sizes)

Technical Considerations

• Concurrency: Implement configurable concurrent export limit (prevent system overload)
• Resilience: Retry failed exports with exponential backoff
• Performance: Leverage existing Rust encoder pipelines from crates/recording
• State Persistence: Save batch queue to local storage for recovery if app crashes

📊 UI/UX

• New "Batch Export" tab in the main recording library
• Drag-and-drop support for adding recordings to queue
• Visual queue panel showing all pending exports
• Toast notifications for operation status updates

🔗 Related

• Builds on existing export functionality in apps/desktop
• Should integrate with the current video export pipeline (TypeScript + Rust interop)

📝 Acceptance Criteria

• Users can select and queue 2+ recordings for batch export
• Progress tracking displays per-item and overall metrics
• Pause/resume works reliably across all queued items
• Failed exports retry automatically (max 3 attempts)
• UI remains responsive during batch operations
• Queue persists across app sessions

This would significantly improve the workflow for content creators and teams using Cap for collaborative video recording and sharing! 🚀