feature: add boot splash screen with embedded TGA logo

- New splash unit (src/prog/splash.pas) displays a centered logo,
  progress bar and status label during kernel boot.  Manually drives
  LVGL rendering + video.Flush since gfxd isn't running yet.
- Embed img/asuro.tga into the kernel via NASM incbin stub
  (src/stub/splash_tga.asm), assembled in compile_stub.sh.
- Build an lv_image_dsc_t at runtime from the decoded TGA pixel data
  and display it at 50% scale using lv_image_set_scale(128).
- Move LVGL init earlier in kernel.pas (right after video enable) so
  the splash screen is available before VFS/drivers/network init.
- Sprinkle splash.update() calls throughout kmain to show boot
  progress (VFS → drivers → buses → network → tests → desktop).
- Fix targa.pas parser: rename Magic→IDLength, remove erroneous Data
  pointer field, compute pixel offset correctly (buffer+18+IDLength),
  advance source pointer per pixel, handle bottom-to-top origin flip.
- Unit tests moved before desktop.init; splash.teardown called at 100%
  just before handing off to the desktop environment.

compile_stub.sh

@@ -4,4 +4,5 @@ echo "======================="
 echo " "
 echo "Compiling Stub..."
 echo " "
-nasm -f elf src/stub/stub.asm -o lib/stub.o
+nasm -f elf src/stub/stub.asm -o lib/stub.o
+nasm -f elf src/stub/splash_tga.asm -o lib/splash_tga.o

src/include/targa.pas

@@ -12,7 +12,7 @@ type
     PTARGAColor = ^TTARGAColor;
 
     TTARGAHeader = packed record
-        Magic: uint8;
+        IDLength: uint8;
         ColorMapType: uint8;
         ImageType: uint8;
         ColorMapOrigin: uint16;
@@ -24,7 +24,6 @@ type
         Height: uint16;
         PixelDepth: uint8;
         ImageDescriptor: uint8;
-        Data : PTARGAColor;
     end;
     PTARGAHeader = ^TTARGAHeader;
 
@@ -35,29 +34,40 @@ implementation
 Function Parse(buffer : puint8; len : uint32) : PTexture;
 var
     header : PTARGAHeader;
-    i, j : uint32;
-    data : PTARGAColor;
-    tex : PTexture;
+    src    : PTARGAColor;
+    tex    : PTexture;
+    x, y   : uint32;
+    dstRow : uint32;
+    topDown: boolean;
 
 begin
-    if (len < sizeof(TTARGAHeader)) then exit;
+    Parse := nil;
+    if len < sizeof(TTARGAHeader) then exit;
 
     header := PTARGAHeader(buffer);
-    if (header^.Magic <> $0) or (header^.ImageType <> 2) or (header^.PixelDepth <> 32) then exit;
-    
-    //Create a new texture
-    tex:= texture.newTexture(header^.Width, header^.Height);
-    tex^.Width:= header^.Width;
-    tex^.Height:= header^.Height;
-    
-    //Copy the data
-    data := PTARGAColor(header^.Data);
-    for i := 0 to header^.Height - 1 do begin
-        for j := 0 to header^.Width - 1 do begin
-            tex^.Pixels[i * header^.Width + j].r := data^.r;
-            tex^.Pixels[i * header^.Width + j].g := data^.g;
-            tex^.Pixels[i * header^.Width + j].b := data^.b;
-            tex^.Pixels[i * header^.Width + j].a := data^.a;
+    if (header^.ImageType <> 2) or (header^.PixelDepth <> 32) then exit;
+
+    { Pixel data starts after the 18-byte header + any ID field. }
+    src := PTARGAColor(buffer + sizeof(TTARGAHeader) + header^.IDLength);
+
+    { Bit 5 of ImageDescriptor: 1 = top-to-bottom, 0 = bottom-to-top. }
+    topDown := (header^.ImageDescriptor AND $20) <> 0;
+
+    tex := texture.newTexture(header^.Width, header^.Height);
+
+    for y := 0 to header^.Height - 1 do begin
+        { Flip vertically when origin is bottom-left (the TGA default). }
+        if topDown then
+            dstRow := y
+        else
+            dstRow := (header^.Height - 1) - y;
+
+        for x := 0 to header^.Width - 1 do begin
+            tex^.Pixels[dstRow * header^.Width + x].b := src^.b;
+            tex^.Pixels[dstRow * header^.Width + x].g := src^.g;
+            tex^.Pixels[dstRow * header^.Width + x].r := src^.r;
+            tex^.Pixels[dstRow * header^.Width + x].a := src^.a;
+            Inc(src);
         end;
     end;
 

src/stub/splash_tga.asm

@@ -0,0 +1,19 @@
+; Embed the boot splash TGA image into .rodata so it is linked
+; directly into the kernel binary.
+;
+; Exported symbols:
+;   _splash_tga_start  – pointer to the first byte of the TGA file
+;   _splash_tga_end    – pointer one past the last byte
+;   _splash_tga_size   – uint32 containing the file size
+
+section .rodata
+
+global _splash_tga_start
+global _splash_tga_end
+global _splash_tga_size
+
+_splash_tga_start:
+    incbin "img/asuro.tga"
+_splash_tga_end:
+
+_splash_tga_size: dd (_splash_tga_end - _splash_tga_start)