Improve project search ranking in Gemma 4 Space

Tune default search grounding depth for Space chat

Add project search grounding to Gemma 4 Space

Align Gemma 4 Space with official multimodal loading path

Fix Gradio examples for Gemma 4 Space app

Fix Gradio compatibility for Gemma 4 Space app

Lazy-load Gemma 4 Space app imports