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>

bindings/cpp/example.cpp

@@ -0,0 +1,33 @@
+// g++ -O2 -std=c++17 example.cpp ../../yapf.c -o example -pthread && ./example ../../other/YAPF.YAPF
+#include "yapf.hpp"
+
+#include <algorithm>
+#include <chrono>
+#include <cstdio>
+#include <fstream>
+#include <iterator>
+
+int main(int argc, char **argv) {
+    const char *path = argc > 1 ? argv[1] : "../../other/YAPF.YAPF";
+    std::ifstream f(path, std::ios::binary);
+    std::vector<uint8_t> bytes((std::istreambuf_iterator<char>(f)), {});
+
+    yapf::Image img = yapf::Image::decode(bytes);
+    double ms = 1e9;                                  // best of 10, as in a running program
+    for (int i = 0; i < 10; i++) {
+        auto t0 = std::chrono::steady_clock::now();
+        img = yapf::Image::decode(bytes);
+        ms = std::min(ms, std::chrono::duration<double, std::milli>(std::chrono::steady_clock::now() - t0).count());
+    }
+    std::printf("%s: %ux%u, %u channels, decoded in %.2f ms, file is %.1f%% of raw\n", path,
+                img.width(), img.height(), img.channels(), ms, 100.0 * bytes.size() / img.size());
+
+    std::vector<uint8_t> again = img.encode();
+    std::printf("re-encoded: %zu bytes, identical to the file: %s\n", again.size(),
+                again == bytes ? "yes" : "no");
+
+    std::vector<uint8_t> gray(64 * 64);
+    for (size_t i = 0; i < gray.size(); i++) gray[i] = uint8_t(i % 64 * 4);
+    yapf::Image(64, 64, 1, gray.data()).save("gray.yapf");
+    std::printf("wrote gray.yapf\n");
+}