IProcess implementation via java.lang.ProcessBuilder / ProcessHandle.
Long-lived process lifecycle: spawn returns a live handle; wait/signal/pipe
act on it. All operations return hive-dsl Result.

Process liveness detection — single source of truth for `is this pid alive?`
semantics across the hive ecosystem.

Use this instead of inlining `kill -0`, `ProcessHandle/of`, or backend-
specific tricks. Liveness check is a system-level concern and belongs in
hive-system (per the IProcess family of protocols), not in callers.

The `LivenessSignal` ADT is the closed sum of valid outcomes:

  :liveness/alive   — pid is owned by a live OS process
  :liveness/dead    — pid was once valid but the process is gone (ESRCH)
  :liveness/unknown — pid is nil/non-integer, or the check itself raised
                      transiently. Callers MUST NOT zombify on :unknown
                      (degrade-soft semantics — protect against false
                      positives during boot races, container migrations,
                      and short-lived OS hiccups).

IWorker implementation — a warm request/response worker over a long-lived
process (hive-system.process IProcess). Requests/responses are newline-
delimited EDN; a monotonic :id correlates each response. Calls are single-
flight via a hive-weave gate (1 permit); reads are timeout-bounded.