fix(dashboard): section detail 404 — use flat /v1/sections/{id} (#10)

The section-detail API route forwarded to /v1/documents/{docId}/sections/
{id}, which the engine does not expose (it only has the flat
/v1/sections/{id}, scoped by the org header). Every section-detail view
returned 'Section not found'. Point it at the correct endpoint.

Author: hallelx2

apps/web/app/api/dashboard/documents/[docId]/sections/[sectionId]/route.ts

@@ -5,10 +5,11 @@ export async function GET(
   _request: NextRequest,
   { params }: { params: Promise<{ docId: string; sectionId: string }> },
 ) {
-  const { docId, sectionId } = await params;
-  const { ok, status, data } = await forwardToCP(
-    `/v1/documents/${docId}/sections/${sectionId}`,
-  );
+  // The engine exposes sections at the flat /v1/sections/{id} path (scoped
+  // by the org header), not nested under the document. docId is only part
+  // of the dashboard URL/breadcrumb.
+  const { sectionId } = await params;
+  const { ok, status, data } = await forwardToCP(`/v1/sections/${sectionId}`);
   if (!ok) {
     return NextResponse.json(data ?? { error: "Upstream error" }, { status });
   }