fix: Improve provider update error handling and add VRM provider settings validation (#887)

* fix: improve error handling for provider updates

Distinguishes failures of active providers from inactive ones.
Propagates errors only for enabled providers, allowing execution
to continue if a non-active provider fails, which avoids unnecessary
interruptions and improves robustness.

* fix: add provider settings validation for forecast requests

Prevents potential runtime errors by checking if provider settings are configured
before accessing forecast credentials.

Raises a clear error when settings are missing to help with debugging misconfigurations.

* refactor(load): move provider settings to top-level fields

Transitions load provider settings from a nested "provider_settings" object with provider-specific keys to dedicated top-level fields.\n\nRemoves the legacy "provider_settings" mapping and updates migration logic to ensure backward compatibility with existing configurations.

* docs: update version numbers and documantation

---------

Co-authored-by: Normann <github@koldrack.com>

src/akkudoktoreos/server/dash/prediction.py

@@ -154,9 +154,7 @@ def LoadForecast(predictions: pd.DataFrame, config: dict, date_time_tz: str, dar
     source = ColumnDataSource(predictions)
     provider = config["load"]["provider"]
     if provider == "LoadAkkudoktorAdjusted":
-        year_energy = config["load"]["provider_settings"]["LoadAkkudoktor"][
-            "loadakkudoktor_year_energy_kwh"
-        ]
+        year_energy = config["load"]["loadakkudoktor"]["loadakkudoktor_year_energy_kwh"]
         provider = f"{provider}, {year_energy} kWh"
 
     plot = figure(