Electron App: Real-time updates

[jongio]

Overview

File system watching for real-time session list updates and attention status changes.

Acceptance Criteria

• Watch session-store.db WAL file for changes (same as TUI's DBWatcher)
• Watch ~/.copilot/session-state/ for attention changes (events.jsonl, lock files)
• Auto-refresh session list within 2 seconds of external changes
• Incremental update: only re-query changed data, not full reload
• Debounce rapid file changes (coalesce within 500ms window)
• Attention status re-scan on file changes
• Visual indicator when refresh is in progress (subtle spinner)
• Manual refresh available (r key / refresh button)
• Watcher pauses when window is minimized/hidden (save resources)
• Watcher resumes immediately when window regains focus
• Handle watcher errors gracefully (file deleted, permissions changed)

Implementation

• Use chokidar for cross-platform file watching
• SQLite PRAGMA data_version as primary change signal
• WAL file mtime as fallback signal
• Session-state directory watching for attention (events.jsonl mtime)
• IPC events push changes from main to renderer