LIZARD 0.2 (alpha)

The second alpha of the Android app. It receives a file shown as a LIZARD code on another screen, and sends one the
same way. It decodes on the GPU through Vulkan where the phone runs it, else on the CPU.

• Android 10 or later, arm64.
• Install: download lizard-0.2-alpha.apk and open it; Android asks to allow installs from that source. It is signed
  with the same development key as 0.1, so it installs over it.
• It does not read 0.1's codes: the format changed (below). Send from fosslabs.dev, which
  serves this release's sender, or from the desktop sender built from this commit.
• Measured on one phone (Samsung S26 Ultra), two codes side by side from the desktop sender at 60 pictures a second on a
  1080p monitor: 3.8 MB/s median and 4.0 max over 13 minutes. The README says what bounds that.
• Built from 5033648. The third-party licenses it carries are in LICENSES.txt.

Since 0.1:

• The code rate follows the frequency: four LDPC codes, from 7/8 on the inner sub-channels to 1/2 on the outer, with
  optimised tables.
• A fourth ring size, 256 band cells a side, for a camera held still close to the screen. The 128 stays the default.
• Files are compressed with zstd, a 4 MiB chunk at a time, where that makes them smaller.
• A file's header and manifest are spread over the frame, so a large file no longer stalls when one part of the code
  reads badly.
• The camera's phase is held to the display's by pilots in every picture, always on.
• The camera's image enhancements (edge enhancement, hot pixel correction and the like) are off where the lens allows.
• The GPU decoder no longer waits to fill a batch.
• Sending paints ahead on the GPU and presents on a fixed schedule, every picture one refresh.
• A received file shows its time and speed; deleting it makes the receiver forget it whole.
• Camera settings are kept per lens.

An alpha: the format still changes, and a sender and a receiver need the same release.