P2-08: Clipboard History panel

[hybridmachine]

Description

Track and access recent clipboard operations.

Implementation

• Track last ~20 clipboard copy/cut operations
• Panel with NSTableView showing clipboard history entries (truncated preview)
• Double-click or Enter to paste selected entry at cursor
• Clear history button
• Keyboard shortcut to show panel (Cmd+Shift+V or similar)
• History stored in memory only (not persisted)

Key Files

• macos/platform/main_phase7.mm