Regression test from #111541: mounts ChatRoutesSurface at a not-yet-registered
path through the real useContributions + registry under the compiler-enabled
vitest ui project, registers the route after mount, and asserts the page
replaces the `:sessionId` chat fallback. Red on origin/main, green with the
snapshot-fed contributedRoutes(). Replaces the equivalent surface test from
#109418 so the workspace surface carries one invariant test.
rahlquist
adbf2103cd