feat(gui): Make the desktop terminal run real commands

The GUI terminal recognised four hardcoded strings and answered everything else
with "Executed: '<cmd>'". It now dispatches to the same LazyBox applet table and
shell builtins the kernel TTY uses, so ls, free, uname, lspci, ktest, neofetch,
sort, cd and the rest all work, with cwd tracked across commands.

LazyBox reports through printk, so before running a command the terminal
installs a printk sink and streams the output into its own scrollback:

  - ANSI SGR codes become per-line colours instead of being stripped.
  - CP437 box-drawing and block characters fall back to ASCII, so the colour
    swatch in neofetch renders as '#' rather than a row of '?'.
  - 256 lines of scrollback, command history on Up/Down, PgUp/PgDn/Home/End.
  - Applets that read the keyboard directly (nano, snake, sh, top) are refused
    with a pointer to the TTY, since they would block the compositor.

The window's paint and event handlers moved out of gui_apps.c into
gui/gui_terminal.c, and gui_gfx.c now draws from the shared lib/font8x8.c table
rather than its own copy.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP

README.md

@@ -41,12 +41,19 @@
 - 🧪 **In-Kernel Test Harness (`kernel/ktest.c`)**:
   - KUnit-style suites with assertion macros, per-case pass/fail reporting and timing.
   - **6 built-in suites, 21 cases, 735 assertions** covering rbtree, kfifo, hashtable, RCU, futex, wait queues, page cache and libcore — runnable from the shell (`ktest`) or the desktop KTest Runner.
+- 🎨 **Boot Logo & Splash Screen (`init/bootlogo.c`, `scripts/mklogo.py`)**:
+  - **Two presentations of one artwork**: an ASCII rendition on the text console and serial line from the first moments of boot, then the real bitmap as a graphical splash once the video driver is up at step [5/14].
+  - **4-bit palette-indexed asset**: 160x160 pixels in 12.5 KB rather than 100 KB, with a transparency mask so the mark composites onto the gradient instead of a flat rectangle.
+  - **Animated progress bar** tied to the real boot stages, held for a minimum duration (`splashtime=<ms>`) so a sub-second boot still shows it; `nosplash`, `nogui` or `text` skip it.
+  - **Regenerable**: `python3 scripts/mklogo.py path/to/logo.png` rewrites `init/logo_data.c` from source artwork.
+- 🔤 **Shared 8x8 Console Font (`lib/font8x8.c`)**: one glyph table behind the framebuffer console, the 2D canvas rasterizer and the desktop compositor, replacing three divergent private copies.
 - 🖥️ **SUB-OS Graphical Desktop Environment (`gui/`)**:
   - **SUB-WM Compositor**: 800x600 TrueColor double-buffered window manager with drag, corner resize, minimize/maximize/restore, edge snapping (left/right/maximize), tile and cascade layouts, and z-ordered painter's-algorithm compositing.
   - **SUB-WT Widget Toolkit (`gui/gui_widgets.c`)**: Immediate-mode controls -- buttons, labels, checkboxes, radios, sliders, list boxes, text fields, tab bars, scrollbars, progress bars, sparklines and badges -- so an app rebuilds its interface from state each frame instead of maintaining a retained widget tree.
   - **Icon Set (`gui/gui_icons.c`)**: 14 hand-drawn 16x16 palette-indexed glyphs, integer-scalable and tintable, driving the desktop grid, start menu and window chrome.
   - **Modal Dialog Layer (`gui/gui_dialog.c`)**: Info, warning, error and confirm dialogs that dim the desktop and take exclusive input, with word-wrapped messages and callback results.
   - **Desktop Shell (`gui/gui_desktop.c`)**: Gradient wallpaper with grid overlay, launcher icon grid, start menu, right-click context menu (tile / cascade / toggle grid), and a taskbar with per-window buttons, live CPU trace, memory badge and RTC clock.
+  - **Terminal Emulator (`gui/gui_terminal.c`)**: dispatches to the real LazyBox applet table and the shared shell builtins, capturing each command's `printk` output through a console sink. ANSI colours are translated per line, CP437 box and block characters fall back to ASCII, and there is 256 lines of scrollback plus command history.
   - **Applications**: Terminal, File Explorer, System Monitor, Task Manager, Kernel Log viewer (live dmesg with severity colouring and scrollback), KTest Runner (drives the in-kernel suites and reports pass/fail), Text Editor, Calculator, Paint Studio, Clock & Calendar, Settings and About.
   - **Keyboard Shortcuts**: `F5` cycle focus, `F6` cascade, `F7` tile, `F8` maximize, `F9` minimize, `Esc` exit to the kernel TTY.
 - ⚡ **Freestanding C++17 OOP Kernel Engine (`kernel/cpp/`)**: