test(raft): E2E replicated writes; wire SQL path to raft node

- Fix runTcpServer to run the already-wired Server (raftNode was assigned
  on a different instance that never accepted clients).
- Cap raft peer connect at 200ms and fan out heartbeats in parallel so a
  dead peer cannot stall AppendEntries to the live majority.
- Add raft_writes_e2e_test: 3-node write replication, follower rejection,
  and post-failover writes; wire into nimble test + gitignore.

.gitignore

@@ -15,6 +15,7 @@ tests/prop_test
 tests/bugfix_test
 tests/nimforum_smoke_test
 tests/raft_e2e_test
+tests/raft_writes_e2e_test
 benchmarks/bench_all
 benchmarks/compare
 clients/nim/tests/test_client