feat: implement lazy graph expansion FindRoute with on-demand /search and transfer depth limit

docs/plans/2026-08-14-lazy-graph-expansion.md

@@ -57,12 +57,12 @@ Implement lazy (on-demand) graph expansion for trip routing within Yandex.Schedu
 - [x] Run tests - must pass before task 3
 
 ### Task 3: Update FindRoute to use lazy expansion with transfer depth limit
-- [ ] Modify `FindRoute` to lazily expand adjacency list during BFS instead of using pre-built edges
-- [ ] Implement transfer depth tracking with max 4-5 transfers limit
-- [ ] Add MCT calculation during lazy expansion (using existing ApplyMCT logic)
-- [ ] Write tests for FindRoute with lazy expansion (various transfer counts)
-- [ ] Write tests for transfer limit enforcement
-- [ ] Run tests - must pass before task 4
+- [x] Modify `FindRoute` to lazily expand adjacency list during BFS instead of using pre-built edges
+- [x] Implement transfer depth tracking with max 4-5 transfers limit
+- [x] Add MCT calculation during lazy expansion (using existing ApplyMCT logic)
+- [x] Write tests for FindRoute with lazy expansion (various transfer counts)
+- [x] Write tests for transfer limit enforcement
+- [x] Run tests - must pass before task 4
 
 ### Task 4: Implement cache-aware search results with TTL policies
 - [ ] Integrate search result caching using existing cache TTL policies (near-term: 2-6h, far-term: 7d)