save/e2e: #51 — wire generateRing attach into resolveJumpTask + spread-limit e2e

- resolveJumpTask: build existingEdgeKeys from all jump routes (both
  endpoints in the save's system set), pass all systems except the
  target as attachCandidates, insert closing routes for each attach.
- save.test.ts: jump test now expects 1–4 fresh systems (was pinned
  to exactly 4); A/B snapshot test stays green (both paths share the
  same resolveJumpTask code).
- e2e/helpers.ts: update stale comment ('4 fresh neighbours' →
  '1–4 new systems').
- e2e/smoke.spec.ts: new test verifying 1–4 mints, all undiscovered,
  each routed to the target, and BFS connectivity of the full graph.

lib/game/save.test.ts

@@ -114,9 +114,10 @@ describe('jumpToSystem success path', () => {
     expect(currentOf(after).id).toBe(target.id)
     expect(after.systems.find((s) => s.id === target.id)!.discovered).toBe(true)
 
-    // Expansion: 4 new undiscovered neighbours around the target, each routed to it.
+    // #51: 1–4 new undiscovered systems minted around the target, each routed to it.
     const fresh = after.systems.filter((s) => !w0.systems.some((p) => p.id === s.id))
-    expect(fresh).toHaveLength(4)
+    expect(fresh.length).toBeGreaterThanOrEqual(1)
+    expect(fresh.length).toBeLessThanOrEqual(4)
     expect(fresh.every((s) => !s.discovered)).toBe(true)
     for (const n of fresh) {
       expect(after.edges.some(([a, b]) => (a === target.id && b === n.id) || (a === n.id && b === target.id))).toBe(true)