Refactor AuthenticatedState to store displayName and uid

The AuthenticatedState interface was updated to directly store the
`displayName` and `uid` properties. Previously, it stored the entire
`CasContent` object, which contained these properties along with others
that were not consistently used. This change simplifies the interface
and reduces redundancy.

routes/(apps)/notes/partials/(admin)/courses.tsx

@@ -7,7 +7,7 @@ import { State } from "$root/routes/_middleware.ts";
 
 // deno-lint-ignore require-await
 async function Courses(_request: Request, context: FreshContext<State>) {
-  return <h2>Welcome to {context.state.session?.displayName}.</h2>;
+  return <h2>Welcome to {context.state.displayName || 'Guest'}.</h2>;
 }
 
 export const config = getPartialsConfig();

routes/(apps)/notes/partials/index.tsx

@@ -7,7 +7,7 @@ import { State } from "$root/routes/_middleware.ts";
 
 // deno-lint-ignore require-await
 export async function Index(_request: Request, context: FreshContext<State>) {
-  return <h2>Welcome to {context.state.session?.displayName}.</h2>;
+  return <h2>Welcome to {context.state.displayName || 'Guest'}.</h2>;
 }
 
 export const config = getPartialsConfig();

routes/(apps)/notes/partials/notes.tsx

@@ -7,7 +7,7 @@ import { State } from "$root/routes/_middleware.ts";
 
 // deno-lint-ignore require-await
 async function Notes(_request: Request, context: FreshContext<State>) {
-  return <h2>Welcome to {context.state.session?.displayName}.</h2>;
+  return <h2>Welcome to {context.state.displayName || 'Guest'}.</h2>;
 }
 
 export const config = getPartialsConfig();