Added Gemini 2.5 Pro, Gemini 2.5 Flash, Gemini 2.5 Flash-Lite

Added the new Gemini 2.5 model family to TypingMind:

• Gemini 2.5 Pro (Stable, no changes from 06-05)

• Gemini 2.5 Flash (Stable, updated pricing from 05-20)

• Gemini 2.5 Flash-Lite (Preview, small reasoning model)