OPT-11 P4: solar forecast and day plan

A Home Assistant solar forecast (Forecast.Solar, Solcast or Open-Meteo
shapes) and the add-on's own hourly house use decide, before each cheap
run, whether the sun will fill each battery before the expensive hours.
Leftover solar then buys from the grid only the shortfall; Cheap hours only
skips the part the sun covers; Solar first never grid-charges. No, stale or
failed forecast: P3 option A exactly (12 digests pinned from 5a4cdc2).

Replay (16 recorded days, forecast errors from Elia's day-ahead BE solar):
year-earlier prices P4 19.15 vs P2 19.33 / option A 19.44 / old trade 18.14;
real 2026 prices P4 29.19 vs 32.26 / 32.01 / 31.40 EUR net.

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

goodwe_controller/config.yaml

@@ -151,6 +151,13 @@ options:
   # switch and a mode on the Batteries screen, kept in the add-on's store.
   # DECISIONS/OPT-11-battery-modes.md.
   battery_modes_enabled: false
+  # OPT-11 P4: a Home Assistant solar forecast (kWh left today; tomorrow's is
+  # optional) and how much of it to count on. Read only with battery modes
+  # on; empty means no day plan (P3 option A). app/solarfc.py lists the
+  # integrations whose sensors fit.
+  pv_forecast_entity: ""
+  pv_forecast_tomorrow_entity: ""
+  solar_trust_pct: 70
 
   # TEL-11 - THE SITE'S PV PRODUCTION, IN WATTS, AND IT IS READ BY NOTHING THAT
   # DECIDES ANYTHING. Optional, empty on every install that does not set it, and
@@ -951,6 +958,9 @@ schema:
 
   estop_fitted: bool
   battery_modes_enabled: bool
+  pv_forecast_entity: str?
+  pv_forecast_tomorrow_entity: str?
+  solar_trust_pct: int(30,100)
   # TEL-11. Optional, and OPTIONAL WITHOUT A COMPANION RULE - unlike
   # `price_now_entity`/`price_avg_entity`, which are legal only while
   # `price_provider` is `off` and make the add-on REFUSE TO START otherwise.