feat(api): implement single ajustement retrieval endpoint

- GET /ajustements/{numEtud}/{idUE}: get ajustement by student numEtud
  and UE id
- Requires employee role

routes/(apps)/notes/api/ajustements/[numEtud]/[idUE].ts

@@ -0,0 +1,43 @@
+import { FreshContext, Handlers } from "$fresh/server.ts";
+import { db } from "$root/databases/db.ts";
+import { ajustements } from "$root/databases/schema.ts";
+import { AuthenticatedState } from "$root/defaults/interfaces.ts";
+import { eq } from "npm:drizzle-orm@0.45.2";
+
+const NOT_FOUND = new Response(
+  JSON.stringify({ error: "Ajustement introuvable" }),
+  { status: 404, headers: { "content-type": "application/json" } },
+);
+
+const FORBIDDEN = new Response(null, { status: 403 });
+
+export const handler: Handlers<null, AuthenticatedState> = {
+  // #50 GET /ajustements/{numEtud}/{idUE}
+  async GET(
+    _request: Request,
+    context: FreshContext<AuthenticatedState>,
+  ): Promise<Response> {
+    if (context.state.session.eduPersonPrimaryAffiliation !== "employee") {
+      return FORBIDDEN;
+    }
+
+    const numEtud = Number(context.params.numEtud);
+    const idUE = Number(context.params.idUE);
+
+    if (isNaN(numEtud) || isNaN(idUE)) {
+      return new Response("Paramètres invalides", { status: 400 });
+    }
+
+    const ajustement = await db
+      .select()
+      .from(ajustements)
+      .where(eq(ajustements.numEtud, numEtud), eq(ajustements.idUE, idUE))
+      .then((rows) => rows[0] ?? null);
+
+    if (!ajustement) return NOT_FOUND;
+
+    return new Response(JSON.stringify(ajustement), {
+      headers: { "content-type": "application/json" },
+    });
+  },
+};