feat: add IMGUI_USE_WCHAR32 support, cross-compile natives, publish to mvn.mrlokop.dev

- Enable IMGUI_USE_WCHAR32 in imconfig.h (ImWchar = uint32_t)
- Extend ImFontGlyphRangesBuilder, ImFontConfig, ImFontAtlas for 32-bit codepoints
- Cross-compile natives for macOS universal, Linux x86_64 (glibc), Windows x86_64
- Publish as org.nnstd.imgui:...:1.90.0-wchar32+mrlokop2 to mvn.mrlokop.dev
- Add BUILDING.md with full rebuild and publish instructions

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

imgui-binding/src/generated/java/imgui/ImFontConfig.java

@@ -347,6 +347,33 @@ public final class ImFontConfig extends ImGuiStructDestroyable {
         nSetGlyphRanges(glyphRanges);
     }
 
+    /**
+     * Convenience overload: encodes int[] codepoint pairs into WCHAR32 short[] layout and calls setGlyphRanges.
+     * Expects int[] pairs [ lo, hi, lo, hi, ..., 0 ] (zero-terminated).
+     * THE ARRAY DATA NEEDS TO PERSIST AS LONG AS THE FONT IS ALIVE.
+     */
+    public void setGlyphRanges(final int[] codepoints) {
+        // count pairs
+        int pairCount = 0;
+        for (int i = 0; i + 1 < codepoints.length; i += 2) {
+            if (codepoints[i] == 0) break;
+            pairCount++;
+        }
+        // each pair = 4 shorts (2 per endpoint), plus 2 terminator shorts
+        final short[] encoded = new short[pairCount * 4 + 2];
+        int out = 0;
+        for (int i = 0; i < pairCount; i++) {
+            final int lo = codepoints[i * 2];
+            final int hi = codepoints[i * 2 + 1];
+            encoded[out++] = (short) (lo & 0xFFFF);
+            encoded[out++] = (short) ((lo >> 16) & 0xFFFF);
+            encoded[out++] = (short) (hi & 0xFFFF);
+            encoded[out++] = (short) ((hi >> 16) & 0xFFFF);
+        }
+        // terminator already zero from array initialisation
+        setGlyphRanges(encoded);
+    }
+
     private native void nSetGlyphRanges(short[] glyphRanges); /*
         THIS->GlyphRanges = glyphRanges != NULL ? (ImWchar*)&glyphRanges[0] : NULL;
     */