Add orionpkg (package manager GUI) + installer locale step

orionpkg/orionpkg.c (~500 lines, native Xlib/Xft):
- Launches with checkupdates (pacman-contrib) to list pending upgrades
- ST_CHECKING: animated spinner while querying
- ST_UPDATES: scrollable package list with name / old ver → new ver columns
- ST_UPDATING: pkexec pacman -Syu in background, live log output,
  progress bar estimated from pacman's (N/M) counters
- ST_DONE / ST_ERROR: success or failure screen
- Refresh (r key), scroll (mouse wheel / arrow keys), Close (Esc/q)
- pacman-contrib added to ISO packages

Installer: add STEP_LOCALE (timezone + keyboard layout):
- Inserted between STEP_DISK and STEP_USER
- Timezone pane: searchable filter input + scrollable list of 37 zones
- Keyboard pane: 20 common layouts with code + description
- Timezone and keyboard passed as args 6/7 to orioninstall
- orioninstall: sets /etc/vconsole.conf and X11 xorg.conf.d keyboard
  config from args; uses selected timezone for localtime symlink

Also:
- Right-click menu: "Software Updates" → orionpkg
- Root Makefile: orionpkg target + install rule
- ISO: orionpkg binary installed, permissions map, gitignore

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

wm/src/menu.c

@@ -14,6 +14,7 @@ static const MenuItem MENU_ITEMS[] = {
     { "System Monitor",    "alacritty -T 'System Monitor' -e htop &"    },
     { "Volume Control",    "pavucontrol &"                              },
     { "System Settings",   "nebula &"                                   },
+    { "Software Updates",  "orionpkg &"                                 },
     { "Display Settings",  "arandr &"                                   },
     { "──────────────────", NULL                                         },
     { "Change Wallpaper",  "orionwallpaper --reset &"                    },