MC3 correctness test profile

Updating:
  The download is always published as mc3-test.mrpack. Its internal version
  identifies the release, but the stable URL does not change.

  To update the same Modrinth App instance, first back it up, then open:
  Settings -> Installation -> Change version
  and select the newly downloaded mc3-test.mrpack. Current Modrinth App reuses
  that instance/profile, including its per-instance Java memory setting, while
  replacing the pack-managed content. Import is only for a separate clean
  instance. Automatic one-click discovery still requires a pack published as
  a Modrinth project.

Logo:
  Modrinth App recognises overrides/icon.png during direct .mrpack import and
  assigns it to the new instance automatically. mc3-logo.png is also included
  at the instance root as a reusable copy for manual selection or export.

Memory:
  Set this instance's maximum memory to 65536 MiB (64 GiB) in the launcher.

The Modrinth .mrpack v1 format contains game files and dependencies only; it
does not have a JVM-memory field. Modrinth App therefore cannot import this
setting from the pack itself.

Profiling:
  In a world, run /mc3 profile start 60 and reproduce a slow vertical drop.
  MC3 writes the JFR recording and JSON summaries into the instance's debug/
  directory even if the render thread freezes.

Rendering:
  Sodium and Iris are installed, with shaders disabled.

  Voxy is installed because it is a mandatory correctness target. MC3 pushes
  delivered sections into Voxy and feeds resident cubes in a configurable far
  prism (voxyViewDistance, default 32 cubes) with the same first-delivery
  gates as the near view; block edits invalidate far sends on the next sweep.
  The far feed still never starts generation — coverage beyond the near view
  grows with exploration and /mc3 pregen. E-LITE is deliberately excluded.
