feat(zui): ZUI system — docking, text editing, scroll, Doxygen docs + cleanup

.gitignore

@@ -428,3 +428,4 @@ SampleProject/
 # Presentation exports
 *.pdf
 *.pptx
+.claude/worktrees/

Resources/Shaders/imgui.frag → Resources/Shaders/zui_draw.frag

@@ -8,12 +8,11 @@ layout(set = 1, binding = 2) uniform sampler LinearClampSampler;
 layout(location = 0) in struct
 {
     vec4 Color;
-    vec4 TexData;
+    vec4 TexData; // xy=UV, z=texIdx
 } In;
 
 void main()
 {
-    // texId derives from pc.index (push constant) - dynamically uniform; nonuniformEXT not needed.
     uint texId  = uint(floor(In.TexData.z + 0.5));
     vec4 texVal = texture(sampler2D(TextureArray[texId], LinearClampSampler), In.TexData.xy);
     fColor      = In.Color * texVal;

Resources/Shaders/zui_draw.vert

@@ -0,0 +1,32 @@
+#version 460 core
+
+layout(location = 0) in vec2 aPos;
+layout(location = 1) in vec2 aUV;
+layout(location = 2) in vec4 aColor; // RGBA8 UNORM — hardware unpacks packed uint32
+
+layout(push_constant) uniform PC
+{
+    vec2  uScale;
+    vec2  uTranslate;
+    uint  uTexIdx;
+    float uFbScale; // UIScale = fb/win; snaps vertices to nearest physical pixel
+}
+pc;
+
+layout(location = 0) out struct
+{
+    vec4 Color;
+    vec4 TexData; // xy=UV, z=texIdx
+} Out;
+
+void main()
+{
+    Out.Color     = aColor;
+    Out.TexData   = vec4(aUV, float(pc.uTexIdx), 0.0);
+
+    // Snap to the nearest physical pixel before projecting.
+    // Prevents sub-pixel drift that blurs glyph quads on non-Retina displays.
+    float fs      = max(pc.uFbScale, 1.0);
+    vec2  snapped = round(aPos * fs) / fs;
+    gl_Position   = vec4(snapped * pc.uScale + pc.uTranslate, 0.0, 1.0);
+}