Wire Razor .razor/.cshtml @inject/@using through the existing scope-aware C# type resolver
instead of a bespoke path: @inject emits a references edge to a sourceless stub, @using
feeds scoping, and the type-resolution + stub-rewire passes now accept Razor sources. A
cross-file injected type resolves to its real definition; an external/undeclared type
fabricates nothing and a qualified inject does not mis-bind a same-named type.
Partially addresses #3187: a bare @inject of a type in a file-scoped namespace still dangles
(same as a bare C# cross-namespace reference without a using), and implicit _Imports.razor
global usings are not yet modeled — left as follow-up, so this does not auto-close the issue.