[Feature request] Allow user to cancel tool execution in french bistro agent

[beaufortfrancois]

I'll merge this and will fix this demo once Chromium has implemented proper support for cancelling execution of declarative tools.

See #224 (comment)

Originally posted by @beaufortfrancois in #224 (comment)

[beaufortfrancois]

FYI I'm working on 8004881: [WebMCP] executeTool signal successfully resets tool pseudo-classes to unblock this issue