Language bindings, KDE thumbnails, yapf compare, in-memory encoding

- yapf_encode() / yapf_free_buffer(): encode to memory; yapf_save uses it
- yapf.c also compiles as C++
- `yapf compare`: size and decode speed of the original format vs YAPF,
  with a lossless check
- bindings with tested examples: C++ (header-only), C# (P/Invoke),
  Rust (crate, builds the C code), Go (cgo), Java (FFM API, Java 22+),
  Zig (@cImport), LuaJIT (FFI), TypeScript types for the JS port;
  Python now encodes in memory
- docs/LANGUAGES.md and examples/ with measured results
- KDE Dolphin thumbnail plugin (KF6, CMake)
- README: honest status for Photoshop / VS Code / Figma (not run in the
  apps yet) and macOS (cross-compiled only), platform table

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

extensions/kde/CMakeLists.txt

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+# YAPF thumbnails for KDE Dolphin (KF6 KIO thumbnail plugin).
+#   cmake -B build -DCMAKE_BUILD_TYPE=Release
+#   cmake --build build
+#   sudo cmake --install build        (or see README.md for a per-user install)
+cmake_minimum_required(VERSION 3.16)
+project(yapfthumbnail LANGUAGES C CXX)
+
+find_package(ECM 6.0 REQUIRED NO_MODULE)
+set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH})
+include(KDEInstallDirs)
+include(KDECMakeSettings)
+include(KDECompilerSettings NO_POLICY_SCOPE)
+
+find_package(Qt6 6.5 REQUIRED COMPONENTS Core Gui)
+find_package(KF6 6.0 REQUIRED COMPONENTS KIO)
+find_package(Threads REQUIRED)
+
+kcoreaddons_add_plugin(yapfthumbnail
+    SOURCES yapfthumbnail.cpp ../../yapf.c
+    INSTALL_NAMESPACE "kf6/thumbcreator")
+set_source_files_properties(../../yapf.c PROPERTIES LANGUAGE C)
+target_include_directories(yapfthumbnail PRIVATE ../..)
+target_link_libraries(yapfthumbnail PRIVATE KF6::KIOGui Qt6::Gui Threads::Threads)
+
+# Register the image/x-yapf file type so Dolphin recognises .yapf files.
+install(FILES ../linux/yapf-mime.xml DESTINATION ${KDE_INSTALL_MIMEDIR} RENAME yapf.xml)

extensions/kde/README.md

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+# YAPF thumbnails for KDE (Dolphin)
+
+Shows previews of `.yapf` files in **Dolphin**, the KDE file dialogs and
+anything else that uses KIO thumbnails.  KDE Frameworks 6 / Plasma 6.
+Files with mipmaps are thumbnailed from the nearest mip level, so even huge
+textures preview instantly.
+
+## Build and install
+
+You need CMake, a C/C++ compiler and the KDE development packages:
+
+| System          | Packages |
+| :-------------- | :------- |
+| Arch / Manjaro  | `sudo pacman -S cmake extra-cmake-modules kio` |
+| Debian / Ubuntu | `sudo apt install cmake extra-cmake-modules libkf6kio-dev qt6-base-dev` |
+| Fedora          | `sudo dnf install cmake extra-cmake-modules kf6-kio-devel qt6-qtbase-devel` |
+| openSUSE        | `sudo zypper install cmake kf6-extra-cmake-modules kf6-kio-devel qt6-base-devel` |
+| NixOS           | `nix-shell kde-shell.nix` (in this folder) |
+
+```sh
+cd extensions/kde
+cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
+cmake --build build
+sudo cmake --install build
+update-mime-database /usr/share/mime
+```
+
+This installs the plugin (`kf6/thumbcreator/yapfthumbnail.so`) and the
+`image/x-yapf` file type.  Then in Dolphin: **Settings → Configure Dolphin →
+Interface → Previews**, tick **YAPF Images**, and turn previews on.
+
+### Without root (per user, also NixOS)
+
+```sh
+cmake -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$HOME/.local
+cmake --build build && cmake --install build
+update-mime-database ~/.local/share/mime
+mkdir -p ~/.config/plasma-workspace/env
+echo 'export QT_PLUGIN_PATH="$HOME/.local/lib/plugins:$QT_PLUGIN_PATH"' > ~/.config/plasma-workspace/env/yapf.sh
+```
+
+Log out and back in, then enable **YAPF Images** in Dolphin's preview settings.
+(Some distributions use `lib64/plugins` or `lib/qt6/plugins`; `cmake
+--install` prints the exact folder.)
+
+## Status
+
+Built against KF6 / Qt 6 and tested by loading the plugin through KDE's
+plugin factory and creating thumbnails (RGBA, RGB, mipmapped, wide images;
+corrupt files are rejected).  Not yet tried inside a running Dolphin.

extensions/kde/kde-shell.nix

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+# Development shell for building the plugin on NixOS: nix-shell kde-shell.nix
+with import <nixpkgs> {};
+mkShell {
+  nativeBuildInputs = [ cmake kdePackages.extra-cmake-modules pkg-config ];
+  buildInputs = [ kdePackages.kio kdePackages.qtbase kdePackages.kcoreaddons ];
+}

extensions/kde/yapfthumbnail.cpp

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+// YAPF thumbnails for KDE Dolphin and other KIO file dialogs.
+// Copyright 2026 Nexoniarz — Apache License 2.0.
+
+#include <KIO/ThumbnailCreator>
+#include <KPluginFactory>
+#include <QImage>
+
+extern "C" {
+#include "yapf.h"
+}
+
+class YapfThumbnailCreator : public KIO::ThumbnailCreator
+{
+    Q_OBJECT
+public:
+    YapfThumbnailCreator(QObject *parent, const QVariantList &args)
+        : KIO::ThumbnailCreator(parent, args)
+    {
+    }
+
+    KIO::ThumbnailResult create(const KIO::ThumbnailRequest &request) override
+    {
+        const QByteArray path = request.url().toLocalFile().toLocal8Bit();
+        yapf_image_t *img = yapf_load(path.constData());
+        if (!img) {
+            return KIO::ThumbnailResult::fail();
+        }
+
+        // Start from the smallest stored mip level that still covers the
+        // requested size; Qt scales the rest.
+        const QSize want = request.targetSize();
+        int m = 0;
+        while (m + 1 < img->mip_levels &&
+               int(img->width >> (m + 1)) >= want.width() &&
+               int(img->height >> (m + 1)) >= want.height()) {
+            ++m;
+        }
+        const int w = qMax(1, int(img->width >> m));
+        const int h = qMax(1, int(img->height >> m));
+        const uchar *px = img->mips[m];
+
+        QImage image;
+        switch (img->channels) {
+        case 1:
+            image = QImage(px, w, h, w, QImage::Format_Grayscale8).copy();
+            break;
+        case 2: {                                   // gray + alpha → RGBA
+            image = QImage(w, h, QImage::Format_RGBA8888);
+            for (int y = 0; y < h; ++y) {
+                const uchar *s = px + size_t(y) * w * 2;
+                uchar *d = image.scanLine(y);
+                for (int x = 0; x < w; ++x, s += 2, d += 4) {
+                    d[0] = d[1] = d[2] = s[0];
+                    d[3] = s[1];
+                }
+            }
+            break;
+        }
+        case 3:
+            image = QImage(px, w, h, w * 3, QImage::Format_RGB888).copy();
+            break;
+        default:
+            image = QImage(px, w, h, w * 4,
+                           (img->flags & YAPF_FLAG_PREMULT_ALPHA) ? QImage::Format_RGBA8888_Premultiplied
+                                                                  : QImage::Format_RGBA8888).copy();
+            break;
+        }
+        yapf_free(img);
+
+        if (image.width() > want.width() || image.height() > want.height()) {
+            image = image.scaled(want, Qt::KeepAspectRatio, Qt::SmoothTransformation);
+        }
+        return KIO::ThumbnailResult::pass(image);
+    }
+};
+
+K_PLUGIN_CLASS_WITH_JSON(YapfThumbnailCreator, "yapfthumbnail.json")
+
+#include "yapfthumbnail.moc"

extensions/kde/yapfthumbnail.json

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+{
+    "CacheThumbnail": true,
+    "KPlugin": {
+        "MimeTypes": ["image/x-yapf"],
+        "Name": "YAPF Images"
+    }
+}