PRICE-01: price_service provider, fallback chain, and the gate read from it

A new price source, `price_provider: price_service`: the owner's price server,
one fixed HTTPS host, a bearer token (new password option
`price_service_token`), wholesale energy only so markup and taxes are added as
for generic_dayahead.

The chain is server, then energy-charts, then the prices the history store
kept. A step counts only if it has a price for now. Each step down and back up
is one log line. With every source down a site plans from what it saved.

No price for now: one status row, one Home plan line and one notification, in
English and Dutch, cleared when a price returns. With this provider the
maintenance charge gate reads the provider's prices and keeps the Home
Assistant rule: the current 15-minute price is at or below today's average.

The token is hidden on the settings page, refused when missing, and taken out
of any error text. Other providers, `off` and the Home Assistant pair take the
road they always took (scripted-day probe against 0ce7d35: one line differs,
the refusal that lists the known providers). See
DECISIONS/PRICE-01-own-price-server.md.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/app/ui_text/en.json

@@ -35,7 +35,7 @@
     "meter_source": {"off": "One grid power entity", "ha_dsmr": "Import and export entities", "mqtt_p1": "Meter over MQTT", "ha_signed": "One net power entity", "homewizard_local": "HomeWizard meter on the network"},
     "meter_phases": {"1": "1 phase", "3": "3 phases"},
     "shadow_mode": {"auto": "Automatic", "on": "Always on", "off": "Off"},
-    "price_provider": {"generic_dayahead": "Day-ahead market price", "custom_formula": "Your own price formula", "manual_csv": "A price file"},
+    "price_provider": {"generic_dayahead": "Day-ahead market price", "custom_formula": "Your own price formula", "manual_csv": "A price file", "price_service": "Your own price service"},
     "log_level": {"trace": "Everything, for support", "debug": "Detailed, to find a problem", "info": "Normal", "warning": "Warnings and errors", "error": "Errors only"},
     "period_days": {"mon-sun": "Every day", "mon-fri": "Monday to Friday", "sat,sun": "Saturday and Sunday", "mon": "Monday", "tue": "Tuesday", "wed": "Wednesday", "thu": "Thursday", "fri": "Friday", "sat": "Saturday", "sun": "Sunday"}
   },
@@ -410,6 +410,8 @@
       "give_would": "Tomorrow: would give power at {at}, {eur} per kWh."
     },
     "cycle_waits": "{name} waits its turn for the monthly cycle.",
+    "no_prices_yet": "No prices yet, maintenance waits.",
+    "no_prices_since": "No prices since {at}, maintenance waits.",
     "step_in": "The batteries step in above {kw}.",
     "step_in_would": "The batteries would step in above {kw}.",
     "period": "This 15-minute period is heading for {kw}.",