Version of SWIFT from April 2026.

Major changes since v2026.01:
 - Released the FLAMINGO model and parameter files used for the original runs in the suite.
 - Added a large range of ci tests and scripts now running on a new dedicated server.
 - Added the Balsara-Kim 2004 ISM example to test feedback on small scales.
 - Added GroupIDs to the sink particle outputs
 - Speed-ups to the star formation task
 - Speed-ups in the star ghost operations by releasing a lock earlier
 - Speed-ups in the gravity operations (especially over MPI) by dropping tasks unnecessarily constructed at distances beyond the FFT mesh.
 - Added tracers for the GEAR model
 - Added SF logger for the star formation from sink particles
 - Added many new variables and modules to the GEAR sink module
 - Split partition.c, scheduler.c, and long-range gravity into smaller files
 - Added an example for the GEAR stellar wind module
 - Minor formatting, code duplication removals, and documentation improvements.