sync-core-after-chat-upgrade

Apply released @aituber-onair/chat updates to @aituber-onair/core and core React examples. This includes aligning dependency versions across core packages, adding or updating core re-exports, synchronizing example model lists, refreshing documentation and changelogs, regenerating lockfiles (npm/yarn/pnpm), and running post-change verification (lint, build, tests). Use this after releasing or upgrading the chat package or when maintainers request that chat changes be propagated into core.