refactor: remove Edit key binding, rename ExtractArchive -> Unpack

- Remove unused Edit key binding (no keys assigned, duplicated Enter)
- Rename ExtractArchive to Unpack across KeyMap struct, DefaultKeyMap(),
  ShortHelp(), FullHelp(), and Model.Update() handler
- Rename handleExtractArchive() -> handleUnpack()
- Update help text, status messages, and dialog titles to 'unpack'

vcom.toml

@@ -4,7 +4,7 @@ right_path = ''
 
 [ui]
 app_title = 'vcom'
-theme = 'catppuccin-mocha'
+theme = 'one-dark'
 icon_mode = 'auto'
 show_title_bar = true
 show_footer = true