Solid package handoff

packages/solid owns only the Solid application shell, typed render props, semantic CSS mapping, specialized ChoiceList, and generic native StandardComponent. It consumes useChat, ChatContainer, Message, InputBar, ThinkingIndicator, and ToolConfirmation from @agentskit/solid@0.4.4.

Never add another controller, reactive store, stream consumer, lifecycle implementation, confirmation engine, or container primitive. Config and session identity are isolated with keyed Solid owners. Owner cleanup delegates cancellation to the upstream binding fixed in AgentsKit #1169.

Checks: pnpm --filter @agentskit/chat-solid lint && pnpm --filter @agentskit/chat-solid test && pnpm --filter @agentskit/chat-solid build.