feat(web): add a web render-intent card for web_search and web_fetch results

web_search and web_fetch returned only model-facing text, whose markdown source
list is lossy (title-or-hostname label, snippet and date concatenated), so a
client could not recover the structured sources. Add a card:'web' result view
with a kind discriminant ('search' carrying structured sources + answer +
truncated, 'fetch' carrying url + statusCode + truncated), projected through
each tool's output.presentationMeta and read back in presentResult. A UI
without the web card falls back to content; the TUI is unchanged. The web
consumer is a follow-up.

packages/core/tools/src/index.ts

@@ -82,6 +82,10 @@ export type {
   GenericResultView,
   TerminalResultView,
   DiffResultView,
+  WebResultView,
+  WebSearchResultView,
+  WebFetchResultView,
+  WebSource,
 } from './presentation.ts'
 
 declare module 'cordis' {