Fry3DX 0.5: builds for Windows, Linux and Android, a phone layout, Apache 2.0

- Apache License 2.0
- Windows: cross-built with clang-cl (cmake --preset windows), a window
  program with its icon; Linux: a portable preset (SDL and the C++
  library inside); Android: android/build_apk.py makes the APK
- tools/package.py packs the downloads; a GitHub workflow builds all
  three and makes a release for a v* tag
- A phone layout (fry_touch, on by default on Android): the UI drawn
  bigger, panels when asked for, a bar of big buttons, one finger to
  turn the view, two to move and pinch, a long press for a right-click;
  files through the phone's file picker
- Settings and autosaves now in a Nexoniarz folder (copied over once)
- README rewritten, the website shows the downloads and the phone

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NMSrd5oe1GpUD7E6d825KP

docs/site.js

@@ -65,6 +65,14 @@
     keys.append(tr);
   }
 
+  const dl = $("downloads");
+  for (const d of F.downloads) {
+    const a = el("a", "download");
+    a.href = F.releases;
+    a.append(el("strong", null, d.os), el("span", "muted", d.what), el("span", "file", "Fry3DX-…-" + d.file), el("span", null, d.how));
+    dl.append(a);
+  }
+
   $("build-text").textContent = F.build.text;
   $("build-steps").textContent = F.build.steps.join("\n");
   $("build-needs").textContent = F.build.needs;