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/rust/examples/demo.rs

@@ -0,0 +1,26 @@
+// cargo run --release --example demo -- ../../other/YAPF.YAPF
+use std::time::Instant;
+
+fn main() -> Result<(), yapf::Error> {
+    let path = std::env::args().nth(1).unwrap_or_else(|| "../../other/YAPF.YAPF".into());
+    let file = std::fs::read(&path)?;
+
+    let mut img = yapf::Image::decode(&file)?;
+    let mut best = f64::MAX; // best of 10, as in a running program
+    for _ in 0..10 {
+        let t = Instant::now();
+        img = yapf::Image::decode(&file)?;
+        best = best.min(t.elapsed().as_secs_f64() * 1e3);
+    }
+    println!("{path}: {}x{}, {} channels, decoded in {best:.2} ms", img.width, img.height, img.channels);
+    println!("file is {} bytes, {:.1}% of the raw pixels",
+             file.len(), 100.0 * file.len() as f64 / img.pixels.len() as f64);
+
+    let again = img.encode()?;
+    println!("re-encoded: {} bytes, identical: {}", again.len(), again == file);
+
+    let px: Vec<u8> = (0..128 * 128).flat_map(|i| [(i % 128 * 2) as u8, (i / 128 * 2) as u8, 128]).collect();
+    yapf::Image::new(128, 128, 3, px).save("rust.yapf")?;
+    println!("wrote rust.yapf");
+    Ok(())
+}