Refactor download history popup to support multiple windows

[timche]

Summary

Refactored the download history popup system to be window-agnostic, allowing the popup to be opened from any window rather than being tied to the main window. This enables better support for multi-window scenarios and improves code maintainability.

Key Changes

• Removed main window dependency: Eliminated the import of main from downloads.ts and replaced hardcoded references to main.window with a parentWindow parameter passed at runtime
• Added parent window tracking: Introduced recentDownloadHistoryParentWindow field to track which window owns the current popup, enabling proper cleanup and bounds calculations
• Renamed for clarity: Changed recentDownloadHistoryPopup to recentDownloadHistoryView to better reflect that it's a view, not a window
• Updated toggle logic: Modified toggleRecentDownloadHistoryPopup() to accept a BrowserWindow parameter and intelligently handle toggling (closes if same window, opens in new window if different)
• Fixed IPC integration: Updated the IPC handler to extract the parent window from the event sender, ensuring the popup opens in the correct window context
• Unified button styling: Refactored both main and Google app titlebar download buttons to use consistent TitlebarIconButton component and naming (RecentDownloadHistoryButton)
• Updated documentation: Added example to CLAUDE.md coding guidelines showing parentWindowBounds as a better alternative to generic names

Implementation Details

• The popup now calculates bounds relative to the parent window's dimensions, with platform-specific handling for Windows (using getContentBounds()) vs other platforms (using getBounds())
• Popup state is properly cleaned up when switching between windows or closing
• All event listeners are attached to the correct parent window instance

https://claude.ai/code/session_01FCKbXY2185E7Jk4QxxVuQA