feat: S8/S9 - trim chargercan.cpp + restore c2/c3 RX for multi-module Tesla OBC

S8 trimmed the 73-entry chargercan.cpp down to 37 entries to fit
libopeninv's 50-slot CANPOS pool — needed because the upstream firmware
silently overflowed the pool and dropped the SKUDAK 0x211 broadcast at
the tail. Without that broadcast the VCU couldn't see idc/udc/tmpobcmax.

S9 restores 8 of the entries S8 dropped: c2/c3 uac, flag, idc, udc.
These turn out to be NECESSARY for 3-module Tesla OBC operation:

- CalcTotals (charger.cpp:41/48) sums c1+c2+c3 idc and takes the max
  udc. Without c2/c3 idc mapped, idc reports only module 1's
  contribution. Bench observed 2.7 kW reported vs 9.7 kW actual EVSE
  draw — exactly the 1/3 ratio expected.
- CheckChargerFaults (charger.cpp:226-261) gates active2/active3
  detection on c2uac/c3uac > 70V. Without those mapped, the active
  bits short-circuit to false — which masked the c2flag/c3flag
  CheckAlive timeout. We were getting away with the trim by accident.

Kept dropped (still need pool headroom for future):
- c2/c3 iac (AC current — c1iac × 3 is a fine proxy, not used in
  aggregation anywhere)
- c2/c3 stt (state — all modules report same value for healthy operation)
- c2/c3 tmp1/2/in (temps — tmpobcmax from c1's 3 probes is sufficient;
  full 9-probe worst-case is a nice-to-have)
- CHAdeMO RX/TX (0x102/0x108/0x109) — Polarity VCU doesn't use CHAdeMO
- 0x368 idle frame — cosmetic only
- hwaclim duplicates on 0x209/0x20B — all modules report identical limits

Pool math: 42 / 50 slots used, 8-slot headroom for future additions.

VERSTR S8 → S9 so any bench reporting -S8 in the openinverter UI is
visibly the regressed build and needs canclear + reflash.

After flash: user must issue `canclear` from the openinverter Commands
tab so the persisted map gets rebuilt from the new chargercan.cpp.
Power-cycle, verify `can p` shows the 8 new c2/c3 lines, then EVSE
test should report ~9.5 kW in the app (was 2.7 kW).

#patch

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

include/param_prj.h

@@ -134,7 +134,12 @@
 // HandleClear callback and stack-overflowed at boot before the terminal
 // came up. Jumping straight to -S7 so any bench that still reports -S6
 // in the openinverter UI is visibly the broken build and gets re-flashed.
-#define VERSTR STRINGIFY(4=VER-S7)
+// -S8 trims chargercan.cpp from 73 → 37 entries so the libopeninv 50-slot
+// pool doesn't silently drop the SKUDAK 0x211 broadcast on rebuild.
+// -S9 restores 8 c2/c3 RX entries (uac/flag/idc/udc per module). -S8 over-
+// trimmed multi-module Tesla OBC support: CalcTotals was summing only
+// module 1's contribution, so reported pack power was 1/3 of actual delivery.
+#define VERSTR STRINGIFY(4=VER-S9)
 
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