test(core): RIP measured with Java FILIUS

RipRun runs rip-chain's three routers in Java FILIUS, each router's random
set by reflection to the core's ripSeed, and writes the frames, every
change of each RIP table and the calls. converge: the tables fill, a ping
at 45 s. expire: R3 falls silent at 10 s; R2 marks its network 16 hops only
at its own next beacon, R1 passes it on at once, the ping gets ICMP 3/0.
Both match: per sending card the same messages at the same times, every
table through the same states. The first 5 s are compared by the state the
tables reach, since Java's routers start one after the other.

Measured on the JDK: Java's pause divides nextFloat() by 3 in float; the
core does too now (a millisecond off in one draw of about 10,000 before).
Scenarios name their RIP routers in the new field rip.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/test/scenario.ts

@@ -51,6 +51,8 @@ export interface Scenario {
     { active?: boolean; lower?: string; upper?: string; gateway?: string; dns?: string; own?: boolean; staticAssignments?: [string, string][] }
   >;
   dhcpClients?: string[];
+  /** Routers with RIP switched on. */
+  rip?: string[];
   /** Records as `name TYPE target` (Java's hinzuRecord: TTL 3600). */
   dnsServers?: Record<string, { records: string[]; recursive?: boolean }>;
   steps: {
@@ -161,6 +163,7 @@ export function snapshotOf(scenario: Scenario): TopologySnapshot {
       ]),
     ),
     dhcpClientConfigurationsByNodeId: new Map((scenario.dhcpClients ?? []).map((node) => [node, { isEnabled: true }])),
+    ripEnabledByNodeId: new Map((scenario.rip ?? []).map((node) => [node, true])),
     switchConfigurationsByNodeId: new Map(
       Object.entries(scenario.switches ?? {}).map(([node, config]) => [
         node,