fix: rebuild stale CAN map on firmware upgrade (new tmpobcmax canary)

The openinverter single-shot MapMessages() guard was using Param::hwaclim
as a "is the map valid" canary. hwaclim has been in every firmware version
for years, so on every upgrade the guard finds it in the saved flash map
and short-circuits — new AddRecv/AddSend entries in chargercan.cpp never
make it into the live canMap.

Symptom on the -S5 bench (verified via openinverter web UI spot values):
tmpobcmax, c1*/c2*/c3* per-module receives, and canenable/idcspnt/udclim
CHAdeMO RX entries were all unmapped despite being in current source.
The Polarity app saw zero charger temperature, zero per-module
current/voltage, and tmpobcmax=0 on 0x211 byte 7.

Fix: switch the canary from hwaclim -> tmpobcmax (added in -S5, never
present in older saved maps) and uncomment canMap->Clear() so the
rebuild starts clean. The early-return guard still kicks in on every
subsequent boot once tmpobcmax is in the map, preserving the original
intent of letting user customizations persist across reboots.

Also bumps VERSTR S5 -> S6 so the openinverter web UI labels this
firmware distinctly from the prior -S5 flash.

#minor

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

include/param_prj.h

@@ -129,7 +129,7 @@
 // SKUDAK customization suffix: bump on every Skudak-side change so the OpenInverter
 // web UI shows a distinct version (e.g. "4=1.20.R-S4") and we can visually confirm
 // the right firmware is flashed. Match the stm32-sine -S<N> convention.
-#define VERSTR STRINGIFY(4=VER-S5)
+#define VERSTR STRINGIFY(4=VER-S6)
 
 /***** enums ******/
 

src/main.cpp

@@ -114,10 +114,22 @@ static void MapChargerMessages()
    float dummyGain;
    bool dummyrx;
 
-   //check sample value, if it is mapped assume valid CAN map
-   if (canMap->FindMap(Param::hwaclim, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
+   // SKUDAK: tmpobcmax is the canary for the -S5+ CAN-map schema. If it's
+   // already mapped, the persistent flash map was built by a firmware that
+   // included the full current set of mappings (including the OBC temp
+   // aggregate and all c1*/c2*/c3* receives) — return early so user
+   // customizations are preserved.
+   //
+   // If tmpobcmax is NOT mapped, the saved map is from an older firmware
+   // that didn't know about it. We must wipe and rebuild from current
+   // chargercan.cpp — without this the OpenInverter single-shot MapMessages()
+   // pattern silently leaves newer params un-mapped on every subsequent
+   // boot, even after flashing fresh firmware (the original guard keyed off
+   // hwaclim, which has existed since the very first version — so it always
+   // short-circuited on upgrade and the new entries were dead code).
+   if (canMap->FindMap(Param::tmpobcmax, dummyId, dummyOfs, dummyLen, dummyGain, dummyAdd, dummyrx)) return;
 
-   //canMap->Clear();
+   canMap->Clear();
 
    ChargerCAN::MapMessages(canMap);