SAFETY-118: read the peak forecast in its own unit

peak_forecast_entity is read through pv.watts() by its unit_of_measurement;
the abs(raw) < 50 size rule is gone. No unit or a non-power unit means the
forecast is not used, with one warning per cause. The validator no longer
claims a kW sensor is taken as watts for this entity.

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/app/validate.py

@@ -1741,11 +1741,12 @@ def _card_note(option: str, spec) -> str:
 
 
 # UX-13: entity options whose number the add-on takes as watts, with no unit
-# conversion. pv.py converts each solar entity's own unit, so those are not here.
+# conversion. pv.py converts each solar entity's own unit, so those are not here,
+# and SAFETY-118 moved the peak forecast there too.
 WATT_ENTITY_KEYS = (
     "meter_entity", "p1_net_entity", "p1_import_entity", "p1_export_entity",
     "p1_phase_net_entities", "p1_phase_import_entities",
-    "p1_phase_export_entities", "batt_entity", "peak_forecast_entity")
+    "p1_phase_export_entities", "batt_entity")
 
 
 # The meter entities each `meter_source` reads through Home Assistant.
@@ -1829,6 +1830,10 @@ def _entity_notes(notes, opts: dict, entities: dict, bad=()) -> None:
             _advise(notes, "warn", (key,),
                     f"{entity} reads in {unit}, but {S(key, where)} is "
                     "taken as watts, so pick a sensor in W.")
+        if key == "peak_forecast_entity" and unit not in pv.WATTS_PER:
+            _advise(notes, "warn", (key,),
+                    messages.peak_forecast_unit(unit) + " Pick a sensor in "
+                    "W or kW.")
         if key in FORECAST_KEYS and unit not in solarfc.KWH_PER:
             _advise(notes, "warn", (key,),
                     f"{entity} does not read in kWh, so pick a solar "