migrate default model IDs from kilo/auto to kilo-auto/frontier and related references across the codebase. update defaults in gateway constants, VSCode provider, tests, UI defaults, and e2e seed. align docs and examples to use kilo-auto/frontier and kilo-auto/free. this is a breaking change for existing configurations
BREAKING CHANGE: update default model IDs to kilo-auto/frontier and kilo-auto/free
kilo/auto and kilo/auto-free no longer used as defaults; update all
references accordingly