UX-45: Home price chart draws one bar per price step the add-on uses

With 15-minute prices the chart now has one bar per quarter (92/96/100),
not hour averages; hourly and static tariffs still draw one bar per hour.
Cheap and dear marks come from the kept priceruns result (battery modes
on) or the arbitrage verdict's two points (off), not a thirds split.
A missing quarter is an empty bar. Removes plan.average_tip (EN/NL).

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

goodwe_controller/app/ui_text/nl.json

@@ -63,8 +63,7 @@
       "estimate_tip": "schatting op basis van gisteren",
       "none_tip": "Geen prijs bekend",
       "no_prices": {"description": "Geen prijzen voor vandaag, dus de grafiek toont alleen het plan."},
-      "list": "Het plan in woorden",
-      "average_tip": "gemiddelde van het uur"
+      "list": "Het plan in woorden"
     },
     "peak": {"name": "Piekgrens", "this_month": "Piek van deze maand", "limit": "Grens", "none": "Nog niets gemeten", "unreadable": "Nu niet leesbaar"},
     "attention": {"name": "Vraagt aandacht", "nothing": "Niets om na te kijken", "to_look": "na te kijken", "details": "Details", "alarm": "Alarm", "warning": "Waarschuwing", "info": "Info"},