Add App.confirm() in common.js: a promise-based dialog styled like the
site's modals, with a title, multi-line message and custom button labels.
Destructive actions use a red OK button and focus Cancel by default;
Escape and backdrop clicks cancel, and Tab stays inside the dialog.
Use it for folding when a check is possible, leaving the table,
confirming showdown winners and deleting tables from the lobby. After the
dialog closes, re-check that the action is still valid (turn not passed,
pot not already awarded, table still listed) before sending it.
Also add a "poker-test" launch config that runs on port 4672 with the
example keys from .env.example, for local browser testing.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>