Fix single-shot blocking-command effect and unsettled span on interrupt

[ghostdogpr]

Two regressions from #152 in the blocking-command path, across all three runtimes.

H1 — a blocking-command effect is single-shot; re-running it hangs

val lease = new DedicatedPool.Lease was evaluated when run(command) was called, so one lease got captured inside the returned effect value. CIO.ensure's finalizer runs cancel() on every exit — including success — driving that lease to the terminal Cancelled state. Re-executing the same value (.retry, .repeat, .forever, …) made Lease.attach fail its CAS, discard the freshly acquired connection, skip the submit, and never invoke the callback: the fiber hangs silently.

It was self-triggering in shipped code: Paged.consume re-runs its single tailNew effect value each poll round, so xConsume delivered one blocking round and then stalled forever on the zio/ce/kyo backends.

Fix: acquire a fresh lease per execution in the standalone, cluster, and master-replica runtimes, expressed as acquireReleaseWith with the lease as the acquired resource (CIO.defer for the acquire — value is strict on the CE backend and would allocate once).

M1 — interrupting an in-flight blocking command never settles observability

The cancel path released the connection but never invoked the tracked callback, so the trace span settled zero times and no CommandCompleted fired.

Fix: thread an onInterrupt settle action through the lease. cancel runs it for a held connection; leaseAndSubmit runs it directly when attach finds the lease already cancelled — an interrupt in the offloaded acquire window or between redirect attempts, where cancel saw no held connection and so could not settle the callback itself. The state CAS keeps this exclusive with the reply's finish, so the callback fires exactly once. It uses ConnectionLost(mayHaveExecuted = true), which in the cluster reply path terminally completes (Fault.Lost(true)) rather than triggering a retry.

Tests

• ZioSmokeSuite: re-running the same blocking effect value twice succeeds each round (fails by hanging without the fix).
• DedicatedPoolSpec: interrupt of an in-flight command settles + discards the slot; interrupt before attach (offloaded-acquire window) still settles; a cancel after a normal reply does not re-fire.

All six client backend cells compile; DedicatedPoolSpec (20) and ZioSmokeSuite (12) pass; scalafmt clean.