Stub documentReviewService in environment-selection route guard tests

PAP-10578 added the documentReviewService stub to two of the three
server test scaffolds whose services/index.js mock crashed createApp
after documentReviewService(db) was wired into issueRoutes. This third
file (environment-selection-route-guards.test.ts) was missed, so it
still threw "No documentReviewService export" on createIssueApp. Add
the same remapOpenSuggestionsForDocument stub to fix the 5 failures.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/src/__tests__/environment-selection-route-guards.test.ts

@@ -91,6 +91,7 @@ vi.mock("../services/index.js", () => ({
   }),
   documentService: () => ({}),
   documentAnnotationService: () => ({ remapOpenThreadsForDocument: async () => [] }),
+  documentReviewService: () => ({ remapOpenSuggestionsForDocument: async () => [] }),
   routineService: () => ({}),
   workProductService: () => ({}),
 }));