feat(gui): Enable direct boot to GUI Desktop with emergency kernel TTY fallback

- Integrate Bochs/QEMU VBE physical LFB mapping directly to hardware video memory (0xFD000000)
- Update kernel boot sequence to directly boot into GUI Desktop by default
- Fall back to Emergency Kernel TTY Mode upon GUI exit (Esc key / Exit menu item)
- Support 'nogui', 'text', 'emergency', and 'single' boot arguments to boot directly into text mode
- Remove frame limits so GUI runs persistently

drivers/video/fb.c

@@ -22,13 +22,25 @@ const fb_info_t* fb_get_info(void) {
     return &fb_info;
 }
 
+void fb_set_hardware_lfb(uint32_t* lfb_addr, uint32_t width, uint32_t height, uint8_t bpp) {
+    if (lfb_addr) {
+        fb_info.address = lfb_addr;
+        fb_info.width = width;
+        fb_info.height = height;
+        fb_info.pitch = width * (bpp / 8);
+        fb_info.bpp = bpp;
+        fb_info.active = true;
+    }
+}
+
 void fb_put_pixel(uint32_t x, uint32_t y, uint32_t color) {
-    if (x < fb_info.width && y < fb_info.height) {
+    if (fb_info.address && x < fb_info.width && y < fb_info.height) {
         fb_info.address[y * fb_info.width + x] = color;
     }
 }
 
 void fb_draw_rect(uint32_t x, uint32_t y, uint32_t w, uint32_t h, uint32_t color) {
+    if (!fb_info.address) return;
     for (uint32_t j = y; j < y + h && j < fb_info.height; j++) {
         for (uint32_t i = x; i < x + w && i < fb_info.width; i++) {
             fb_info.address[j * fb_info.width + i] = color;