Handle %-scaled charge/discharge rate entities during inverter calibration and control writes

[Copilot]

Predbat assumed charge_rate/discharge_rate entities were watt-scaled and wrote raw W values during calibration/control. For integrations exposing signed/percent controls (e.g. -100..100 %), this caused service_validation_error writes and persistent unit-mismatch noise.

• Rate unit detection + conversion path

  • Added %-entity detection for configured charge_rate / discharge_rate entities.
  • Added conversion helpers to translate:
    • read path: % -> W (for internal control logic)
    • write path: W -> % (for service writes)
  • Keeps existing W behavior unchanged for watt-native entities.

• Signed percent discharge handling

  • For signed ranges (e.g. min < 0 < max), discharge writes are sign-adjusted (negative) and clamped to entity bounds.
  • For unsigned percent ranges, discharge remains positive and clamped within configured limits.

• Control-loop integration points

  • Updated both current-rate reads and target-rate writes:
    • get_current_charge_rate
    • get_current_discharge_rate
    • adjust_charge_rate
    • adjust_discharge_rate

• Regression coverage

  • Added focused inverter test for a shared %-scaled rate entity mapped via charge_rate/discharge_rate, verifying correct charge (+%) and discharge (-%) writes.

if self._rate_entity_uses_percent(discharge_rate_entity):
    discharge_rate_percent = self._rate_watts_to_percent(discharge_rate_entity, new_rate, discharge=True)
    self.write_and_poll_value("discharge_rate", discharge_rate_entity, discharge_rate_percent, fuzzy=5, required_unit="%")
else:
    self.write_and_poll_value("discharge_rate", discharge_rate_entity, new_rate, fuzzy=..., required_unit="W")

• Fixes charge_rate/discharge_rate calibration writes fail with service_validation_error when the underlying entity is scaled in % rather than W #4671

[springfall2008]

Closing as there is already a percent setting