Adds /clusters/{ClusterId}/drivers/new picker page (Task 3.1). Renders
a 9-card Bootstrap grid — one card per driver type — each linking to
/clusters/{ClusterId}/drivers/new/{slug}. No data fetch; type list is
hardcoded. Route collides with DriverEdit.razor's same directive; Task
3.3 removes the duplicate to resolve the runtime ambiguity.
Joseph Doherty
c0ce5d02bd