v0.9.33

Derive PV string current from power/voltage (eg4_web_monitor #243).

EG4 hybrid inverters expose no PV-current Modbus register (input regs 72-74 read 0 even while producing, verified live on 18kPV + FlexBOSS21) and the cloud API has no PV-current field. pvN_current is now derived as P/V in both the Modbus and HTTP runtime builders and exposed as computed inverter properties; regs 72-74 are de-routed. Adds pv4-6_current for >3-string models.