## Summary
`Find_TwoPathfindsOverlappingChunks_PromoteToBuildOnSecondFind` fails intermittently in CI with `second Find through overlapping chunks must promote (got 0 builds)`.
**Cause:** `SecondTouchAfterWindow_RestartsTheCount` and `TwoFindsAcrossTheWindow_DoNotPromote` set `StepCache.Instance.MissPromotionWindowMs = 1` and never restore it, and `Clear()` does not reset it. Both classes share the `Sequential Pathfinding Tests` collection, so when a lifecycle test runs first, the promotion test's two Finds have to land within 1 ms of each other. On Linux, `Environment.TickCount` moves in coarse steps of several ms, so even a sub-millisecond test can see the window lapse. The second Find then restarts the miss count instead of promoting. On Windows the ~15.6 ms tick nearly always reads the same value for both Finds, which is why it didn't reproduce locally.
**Fix (tests only):**
- `StepCacheLifecycleTests` implements `IDisposable` and restores the window after each test.
- The promotion test sets the window it depends on (30 s) instead of inheriting it.
## Test plan
- [x] Reproduced deterministically: with a temporary 20 ms sleep between the two Finds, the test fails whenever the lifecycle tests run first and passes when run alone
- [x] With the sleep still in, the test passes with the Dispose restore alone and with both fixes
- [x] All pathfinding tests pass (123/123) with the sleep removed
225c634bf7