Add keyboard shortcuts for file browser navigation

[ringo380]

Description

Add keyboard shortcuts to improve file browser navigation efficiency.

Proposed Shortcuts

• ⌘↑ - Navigate up one directory
• ⌘[ / ⌘] - Back / Forward in history
• ⌘R - Refresh current directory
• ⌘F - Focus search field
• Space - Quick Look selected file
• Enter - Open folder / Quick Look file
• ⌘⌫ - Delete (with confirmation)
• ⌘N - New folder

Implementation

• Add keyboard event handlers to FileBrowserTab
• Follow macOS Finder conventions where possible