feat(ui): implement full UI layer for all modules

Add interactive island components and server partials for notes,
students, and admin modules, following the Figma prototype design.

- static/styles/ui.css: shared component library (buttons, tables,
  chips, cards, filters, tabs, form inputs)
- notes: NotesView (student grade view with UE cards, promo tabs,
  weighted averages), AdminConsultNotes, AdminUEs islands + partials
- students: ConsultStudents (list/filter/delete), AdminPromotions
  (CRUD) islands + partials
- admin: AdminModules, AdminUsers, AdminRoles islands + partials
- All partials use State type with unknown cast for session access

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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

@@ -3,10 +3,41 @@ import {
   makePartials,
 } from "$root/defaults/makePartials.tsx";
 import { FreshContext } from "$fresh/server.ts";
-import { State } from "$root/routes/_middleware.ts";
+import { State } from "$root/defaults/interfaces.ts";
 
-export function Index(_request: Request, _context: FreshContext<State>) {
-  return <h2>Welcome to Admin.</h2>;
+// deno-lint-ignore require-await
+export async function Index(
+  _request: Request,
+  context: FreshContext<State>,
+) {
+  return (
+    <div class="page-content">
+      <h2 class="page-title">Administration</h2>
+      <p>
+        Bienvenue{" "}
+        <strong>
+          {(context.state as unknown as { session: Record<string, string> })
+            .session.displayName}
+        </strong>
+        .
+      </p>
+      <p>
+        Gérez les{" "}
+        <a href="/admin/modules" f-partial="/admin/partials/modules">
+          modules
+        </a>
+        ,{" "}
+        <a href="/admin/users" f-partial="/admin/partials/users">
+          utilisateurs
+        </a>
+        ,{" "}
+        <a href="/admin/roles" f-partial="/admin/partials/roles">
+          rôles
+        </a>{" "}
+        depuis la barre de navigation.
+      </p>
+    </div>
+  );
 }
 
 export const config = getPartialsConfig();