Migrate @waniwani/sdk 0.18 → 0.19

A self-contained migration for the single hop from 0.18.x to 0.19.x (the first published 0.19 release is 0.19.1; 0.19.0 was never published to npm). Apply it when a project on 0.18 is moving to 0.19. It covers only that jump; for other version boundaries use the matching migrate-waniwani-sdk-<from>-to-<to> skill, or the general procedure in the SDK's changelog.

Precondition: the project is on @waniwani/sdk@0.18.x. If it is on an older version, migrate up to 0.18 first (each jump ships its own migration skill); if it is already on 0.19+, there is nothing to do here.

What 0.19 changes

Flow interrupt({ suggestions }) values now also render as clickable pills above the input in the Waniwani chat widget, gated by a named origin list. Almost all of it is additive; the one break:

• suggestion.clicked gained a required properties.origin field — "channel" | "page" | "flow" | "followup", reporting which provider supplied the clicked pill. On 0.18.x the payload was { text, index }. The field is part of WidgetEventDetail / WidgetEvent from @waniwani/sdk/chat.

Also shipped (no action required):

• SuggestionsConfig.origins (SuggestionOrigin[]) replaces the dynamic boolean on the <ChatEmbed> primitive. dynamic is deprecated but still works: true maps to every origin, false to none, origins wins when both are set.
• suggestionOrigins on <WaniwaniChat> overrides and data-suggestion-origins on the <script> embed. Default everywhere is ["channel", "page", "followup"] — flow-driven pills stay opt-in.
• Flow tool results always carry _meta["waniwani/suggestions"] (exported as SUGGESTIONS_META_KEY / SuggestionsMeta). Additive; hosts that ignore _meta are unaffected.

Not affected: reading widget events through onEvent — origin is a new, always-populated field, so existing readers keep compiling and running. Other MCP hosts (ChatGPT, Claude) see no behavior change.