`set display.flip 0|1` (also off/on) turns the panel 180 degrees from its
compiled DISPLAY_ROTATION, persisted in MQTTPrefs alongside display.timeout
and applied live without a reboot.
Adding 2 to the compiled rotation rather than setting an absolute value keeps
portrait portrait and landscape landscape, so the DisplayViewport geometry
never changes with it and the setting cannot produce a nonsensical mix.
DisplayDriver gains a defaulted no-op setFlipped(), so no other display
driver is affected.
The compiled rotation was verified identical across `pio run` and `build.sh`
on two machines (movi a11, 2 at the setRotation call site), yet the panel read
upside down for one tester and upright for another - which is what a board
mounted either way up looks like. No single compiled constant satisfies both,
so orientation becomes a setting rather than another rebuild.
Runtime-only, like display_timeout_secs: LegacyV1MQTTPrefs and the frozen
binary payload sizes are untouched, and the JSON group is an append that older
firmware skips.
agessaman
f3c81b559b