The OpenInverter web UI displays the firmware version from the 'version'
parameter (entry 2001), which expands VERSTR. Out of the box this reads
'4=1.19.R' (upstream version, no Skudak indicator). With this change it
reads '4=1.19.R-S1' so we can visually confirm we're running the Skudak
fork and not stock OpenInverter firmware.
Matches the convention already used in stm32-sine ('-sine-S6' / '-foc-S6')
where the -S<N> suffix bumps on each Skudak-side change.
Verified: 'strings stm32_charger.bin | grep S1' shows '4=1.19.R-S1' in the
built artifact.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Bastian de Byl