UX-08 2c review: unit settings anchor to inverters, plainer texts

- messages.setting() for one inverter in the list reads
  “Inverter rating” for inverter-b (inverters.max_w), so the config panel
  files per-unit reasons under `inverters`, where the value is changed.
- The tariff card and plausibility reasons name
  “Distribution, levies and VAT” (price_taxes_eur_kwh) again.
- The wrong-direction reasons say "safety stop", the sign_disagree_w
  option says what it protects, and the roster, price-entity,
  integrator_max_w and capacity_kwh texts read more plainly.
- NL: stuurprint -> stuurmodule, "De piekbeperking".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/app/custom_formula.py

@@ -292,7 +292,8 @@ _LEGS = {
         neg_factor="Put the minus sign on the offset, not on the factor",
         card_required=True,
         card_note="The add-on needs it to check your two numbers",
-        card_causes="that network charges are not in the offset",
+        card_causes=("that network charges are in “Distribution, levies and VAT” "
+                     "(price_taxes_eur_kwh), not in the offset"),
     ),
     EXPORT_FORMULA_OPTION: _Leg(
         option=EXPORT_FORMULA_OPTION,
@@ -678,10 +679,8 @@ def parse_export_formula(value):
 def card_refusal(spec: FormulaSpec, delta: float) -> str:
     """The sentence an operator reads when their formula misses its own card.
 
-    ⚠️ IT NAMES THE DISCREPANCY AND THE SIX WAYS IT HAPPENS. "Invalid
-    configuration" would be true and useless: every one of these errors looks
-    exactly like a working tariff from the status page, which is why the check
-    exists at all.
+    It names both numbers and what to check. The usual causes are in DOCS.md,
+    because each of these errors looks like a working tariff on the status page.
     """
     got = in_card_units(spec, spec.card_index_eur_per_mwh)
     leg = _LEGS[spec.option]
@@ -744,9 +743,9 @@ def implausible_all_in(spec: FormulaSpec, taxes_eur_kwh: float):
         return None
     return (
         f"{spec.option} gives {energy:.5f} EUR/kWh for energy and "
-        f"{all_in:.5f} EUR/kWh in total on its own card, outside the "
-        f"plausible band of {PLAUSIBLE_LO_EUR_KWH}-{PLAUSIBLE_HI_EUR_KWH} "
-        f"EUR/kWh. Check \"units\" against the unit beside your formula.")
+        f"{all_in:.5f} EUR/kWh with “Distribution, levies and VAT” "
+        f"(price_taxes_eur_kwh), outside the plausible band of "
+        f"{PLAUSIBLE_LO_EUR_KWH}-{PLAUSIBLE_HI_EUR_KWH} EUR/kWh. Check \"units\" against the unit beside your formula.")
 
 
 def implausible_injection(spec: FormulaSpec):