feat: cascade deletes, student notes, import popups, module reorganization

- Cascade delete on all entities (student, module, UE, user, role, promotion)
- Fix Response body reuse bug (factory functions instead of constants)
- Student note viewing via CAS uid (strip non-digit prefix)
- Fix middleware page visibility for students in LOCAL mode
- Import result popup component (shared across all import pages)
- Fix student import to use numEtud from Excel
- Bulk student selection with promo change and delete
- Move UE/UE-Module API and pages from notes to admin module
- Move promotions page from students to admin module
- Multi-year maquette import with per-year promo selection
- Inline promo creation in maquette import
- Static Excel templates (students, notes, maquette)
- Fix XLSX export using blob download instead of writeFile
- Allow students to read modules list (GET /modules)

routes/(apps)/students/partials/(admin)/promotions.tsx

@@ -1,18 +0,0 @@
-import {
-  getPartialsConfig,
-  makePartials,
-} from "$root/defaults/makePartials.tsx";
-import { FreshContext } from "$fresh/server.ts";
-import { State } from "$root/defaults/interfaces.ts";
-import AdminPromotions from "../../(_islands)/AdminPromotions.tsx";
-
-// deno-lint-ignore require-await
-async function Promotions(
-  _request: Request,
-  _context: FreshContext<State>,
-) {
-  return <AdminPromotions />;
-}
-
-export const config = getPartialsConfig();
-export default makePartials(Promotions);