Task 542: dag.rs + E2E Summary Page Tests

Status: DONE

Summary

Rust dag.rs (3 new tests, 33→36)

1. find_paths on complex DAG: two paths from src0→r0 (via a0 and via a1)
2. impact_analysis on complex DAG: src0 cascades to 4 nodes, src1 to 3, param0 to 2
3. layout on complex DAG: data sources left of reports in layered layout

E2E reports.spec.ts (1 new test, 261 total)

1. attitude-control has cross-reference links to episode reports

Impact

dag.rs now tests complex multi-path scenarios beyond simple linear/diamond topologies. E2E attitude-control page reaches 7 dedicated tests (was 6).