swarm: durable, inspectable work-tracking journal (worktrack.el)

Single-writer append-only JSONL journal keyed by correlation ID: swarm +
worker + convergence records, reconstructable into a status report. Optional
engram mirror via POST /api/node when ENGRAM_URL is set. Coordinator is the
only writer (workers return structured results), which is race-free and
enforces Swarm containment rule 3 by construction.

Also prototype now_millis/now_ns in el_runtime.h (defined in el_runtime.c but
unprototyped — blocked any El program needing a real ms clock under clang 21).

Test proves durability + inspectability end-to-end.

lang/swarm/tests/test_worktrack.el

@@ -0,0 +1,38 @@
+// test_worktrack.el — durability + inspectability of the work-tracking journal.
+
+fn main() -> Int {
+    let corr: String = "test-" + uuid_v4()
+
+    // record a swarm lifecycle
+    let p1: String = json_set("{}", "input_count", "3")
+    worktrack_append("swarm.created", corr, "swarm-1", p1)
+    worktrack_append("worker.started", corr, "worker-001", "{}")
+    worktrack_append("worker.started", corr, "worker-002", "{}")
+    worktrack_append("worker.completed", corr, "worker-001", "{}")
+    worktrack_append("worker.failed", corr, "worker-002", "{}")
+    worktrack_append("swarm.completed", corr, "swarm-1", "{}")
+
+    // inspect: reconstruct the report from the durable journal
+    let report: String = worktrack_swarm_report(corr)
+    print("report=" + report)
+
+    let recs_n: Int = el_list_len(worktrack_records(corr))
+    print("records=" + int_to_str(recs_n))
+
+    let state: String = json_get_string(report, "state")
+    let completed: Int = str_to_int(json_get_string(report, "workers_completed"))
+    let failed: Int = str_to_int(json_get_string(report, "workers_failed"))
+
+    if str_eq(state, "completed") {
+        if completed == 1 {
+            if failed == 1 {
+                if recs_n == 6 {
+                    print("PASS worktrack")
+                    return 0
+                }
+            }
+        }
+    }
+    print("FAIL worktrack")
+    return 1
+}