Kiro CLI: Switch to V3 at Chat Start and Model Fallback Notices

This release shows a startup prompt inviting you to switch to V3 as part of a gradual rollout. It also adds V3 model fallback notices, keeps more of your V2 agent access when you upgrade agents to V3, and fixes screen reader, tmux, and knowledge search issues.

[Switch to V3 when you start a chat] The startup prompt is rolling out gradually before V3 becomes the default with CLI 3.0 at the end of October, so you may not see it right away. When it appears, choose Switch to V3 and upgrade my configs to save V3 as your default harness, enable automatic agent upgrades, and start migrating your custom agent configurations. You can also try V3 anytime with `kiro-cli --v3`. Read the Kiro CLI V3 rollout announcement for details.

[See when a V3 turn moves to another model] In V3 sessions, when a model refuses a request or is unavailable and the turn moves to another model, the transcript now shows a notice. You can tell that a different model continued the turn instead of wondering why a reply changed. Learn about model fallback notices.

[Improvements] Upgraded agent permissions: When you change a V2 trust setting in an upgraded agent whose generated V3 fields are unchanged, Kiro CLI refreshes the matching V3 permissions. Learn more

[Fixes] Screen readers now follow streaming replies in the full TUI through the Screen reader option in `/settings display`. Learn more

[Fixes] Upgrading an agent to V3 now preserves its V2 workspace read access and `fs_read` skill trust. Learn more

[Fixes] Knowledge search in Classic and V2 no longer silently drops a chunk from a small knowledge base. Learn more

[Fixes] Scrolling back in tmux no longer shows a screen of blank rows after long replies

[Fixes] Launching Kiro CLI after output without a trailing newline no longer draws the UI at an offset

[Fixes] Fixed garbled text and stray characters around icons in chat on some Linux terminals and remote desktops