fix(fox): clamp fdpwr_max at the corrected capacity instead of a fudge margin

Cap at inverter_capacity directly now that capacity_watts() already
corrects half-kW deviceTypes - the earlier +999W tolerance was a blunter
hack that could let a genuinely bogus fdpwr reading through undetected.

Author: springfall2008

apps/predbat/fox.py

@@ -1494,7 +1494,7 @@ async def get_scheduler(self, deviceSN, checkBattery=True):
             # XXX: Fox seems to be have an issue with FD Power max value being too high, cap it at the inverter capacity
             # (inverter_capacity is already corrected for half-kW deviceTypes by capacity_watts())
             if inverter_capacity:
-                self.fdpwr_max[deviceSN] = min(inverter_capacity + 999.0, self.fdpwr_max[deviceSN])
+                self.fdpwr_max[deviceSN] = min(inverter_capacity, self.fdpwr_max[deviceSN])
 
             # Min SOC On grid can change as Predbat writes reserve so this must be the real min
             self.fdsoc_min[deviceSN] = result.get("properties", {}).get("fdsoc", {}).get("range", {}).get("min", 10)