Battery cards and solar share slider: docs and screenshots for current UI - #1180

pairs with evcc-io/evcc#33434 and evcc-io/evcc#32104

The battery page becomes the default layout and the solar share slider replaces the power-based thresholds as the way to allow grid power in smart mode. Docs and screenshots now match the current UI.

• Battery page: priority, buffer and auto-start paragraphs reworded to the new sentence-style settings, discharge lock option name updated
• Solar surplus charging: "Not enough surplus?" section explains the solar share slider with a new screenshot, delays point to the charging point configuration, power thresholds are no longer described
• FAQ winter tip and loadpoints reference point to the slider, MQTT API lists the solarShare topic
• English compact anchors on the solar charging subheadings
• All screenshots regenerated with the current binary, only visually changed ones kept: battery cards, loadpoint settings with solar surplus section, smart mode wording, vehicle settings layout, plan strategy line, session details, white-label menu
• Recipes fixed for the changed Always charge dropdown and plan strategy toggle

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