A name with no spaces (an agent name, a path, a URL, an id) pushed the
document wider than a phone and made the page scroll sideways.
- page header: on a phone the header is a wrapping column, which sizes
its one line to the widest item. Make it a non-wrapping column and let
the title and supporting line break anywhere.
- agent form: the back button, the collection and name chips, the agent
page facts and the connection group heading now wrap long text.
- add e2e/no-horizontal-overflow.spec.js: it draws the main pages with
unbroken long content at 390 and 768 px, light and dark, and asserts
that the document is not wider than the window.
Assisted-by: Claude:claude-sonnet-5-5