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/messages.py

@@ -788,6 +788,25 @@ def row_no_peak_forecast() -> str:
             "the peak limit")
 
 
+def peak_forecast_unit(unit, lang="en") -> str:
+    """SAFETY-118. The 15-minute demand forecast has a number but no power
+    unit, so it is not used. `unit` is "" for none. One sentence, for the log
+    line, the status row and the settings page. Log lines stay English."""
+    if lang == "nl":
+        return ("De kwartierprognose heeft geen eenheid, dus ze wordt niet "
+                "gebruikt." if not unit else
+                "De kwartierprognose heeft geen vermogenseenheid, dus ze "
+                "wordt niet gebruikt.")
+    return ("The 15-minute demand forecast has no unit, so it is not used."
+            if not unit else
+            "The 15-minute demand forecast is not in a power unit, so it is "
+            "not used.")
+
+
+def row_peak_forecast_unit(unit) -> str:
+    return peak_forecast_unit(unit)
+
+
 def row_peak_guard_waiting() -> str:
     return "Peak guard: no decision yet, control has not run"
 
@@ -1229,6 +1248,8 @@ def status_samples() -> list:
         ("row_no_estop", AMBER, row_no_estop()),
         ("row_estop_fitted", GREEN, row_estop_fitted()),
         ("row_no_peak_forecast", AMBER, row_no_peak_forecast()),
+        ("row_peak_forecast_unit", AMBER, row_peak_forecast_unit("")),
+        ("row_peak_forecast_unit", AMBER, row_peak_forecast_unit("kWh")),
         ("row_peak_guard_waiting", AMBER, row_peak_guard_waiting()),
         ("row_pv", GREEN, row_pv(3200, 2)),
         ("row_pv", GREEN, row_pv(1800, 1, True)),