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/index.html

@@ -64,6 +64,7 @@
 
     <section id="get">
       <h2>Get it</h2>
+      <div class="downloads" id="downloads"></div>
       <p id="build-text"></p>
       <div class="code"><button class="copy" id="copy">Copy</button><pre id="build-steps"></pre></div>
       <p class="muted" id="build-needs"></p>
@@ -77,7 +78,7 @@
 
   <footer>
     <p>Fry3DX, made by <a id="author" href="#"></a>.</p>
-    <p class="muted">Sky pictures from Poly Haven (CC0).</p>
+    <p class="muted">Open source under the Apache License 2.0 · Sky pictures from Poly Haven (CC0).</p>
   </footer>
 
   <script src="content.js"></script>