[Internal Testing] Promote Gemini 3.1 Flash Lite to GA and support Gemini 3.5 Flash#27704

sripasg wants to merge 2 commits into

release/v0.42.0-nightly.20260512.gc987b9939google-gemini/gemini-cli:release/v0.42.0-nightly.20260512.gc987b9939from

xcodegcli_release_branch_add_35_flashgoogle-gemini/gemini-cli:xcodegcli_release_branch_add_35_flashCopy head branch name to clipboard