Gemini lineup update

Added: gemini-3.8/3.7/3.6-flash, gemini-3.5-flash-lite, gemini-2.5-flash-lite
Changed: Gemini Pro repriced to 40% of list; Flash 60%; Flash-Lite 85% Gemini-3-flash-Removed: gemini-3-flash-preview (existing requests unaffected)