Help text should use platform-specific key names (Option instead of meta on Mac)

Description

When running on macOS, help text and keyboard shortcut documentation refers to the "meta" key instead of using Mac-specific terminology like "Option" or "⌥".

Since Claude Code knows the platform it's running on, the help should adapt to show familiar key names:

• On Mac: "Option" or "⌥" instead of "meta"
• On Mac: "Command" or "⌘" where applicable

Current behavior

Help shows generic terminology like "meta+M" regardless of platform.

Expected behavior

On macOS, help should show "Option+M" or "⌥M" to match what users see on their keyboard.

Environment

• macOS (Darwin)