Alabaster Dawn Android port v0.6.1

v0.6.1

A bugfix for the side menu's picture position: with the picture aligned Top or Bottom, mouse
clicks landed nowhere near the thing clicked. Centre was unaffected.

• The port moved the picture where the engine could not see it. The engine's own mouse mapping
  (Input.getMouseCoordsC + DISPLAY_SCALE.transformMouse) reads the canvas element's offsetTop
  and then subtracts a centred letterbox (deltaY/2) from it — the engine believes the picture sits
  in the middle of the canvas element. The port changed only object-position, which moves the
  picture inside the element without moving the element, so every click was interpreted deltaY/2
  below the picture: half the black band. On a 1080x2340 phone at the default 640x360 rung that is
  866 px — the click lands on another part of the screen.
• Now the element's layout box moves (top = desired − deltaY/2) and the picture stays centred
  inside it, which is the box the engine measures from, so both sides agree again. Works in both
  display scales (sharp-pixels off and on), is recomputed every frame, and changes nothing about
  the picture's size or where it is drawn — only where the input thinks it is.
• Verified by booting the real engine in a browser and driving its own input pipeline with real mouse
  events: the same point on the picture now maps to the same game coordinate in Top, Centre and
  Bottom. The old code mapped the picture's centre to y = -280.8 instead of y = 180 in the same
  harness. node android/tools/test-shim-diagnostics.mjs grew 11 checks for this (24/24 green; 7 of
  them fail against the pre-fix shim).

Nothing else changed.

Full release notes: docs/release-notes-0.6.1.md
Install, requirements and known limitations: README