Make aggregate ONNX gates execute for real

Reference-count the process-global ONNX Runtime across embedder and routing-head sessions, make close idempotent, and require named proof that both aggregate routing gates executed rather than self-skipped (V-716). Owner explicitly requested direct commits to master.

JOURNAL.md

@@ -210,3 +210,20 @@ pops only the active top before resuming the flow underneath.
 passes (162.310s for mavend; every package green). Focused structural
 possession, repair-pointer, nested-stack, and repaired-clarify tests pass under
 the race detector.
+
+### ONNX test/runtime lifecycle
+
+V-716 found that each embedder constructor tried to initialize ONNX Runtime,
+while `Close` destroyed only its session. In one package process the first
+model-aware test ran and later tests converted “already initialized” into a
+green skip. The router now owns the process-global environment through
+reference-counted leases held by each embedder and routing-head session; the
+last owned lease performs cleanup, and close is idempotent.
+
+The router and mavend test packages hold a lease across their model gates.
+`make eval-router` additionally requires proof that both named aggregate gates
+actually executed. In one process the classifier baseline scored 72/96 and the
+routing heads 93/96; destination was 11/33 and 25/33 respectively, and ecosystem
+reach remained 28/30. The lifecycle reacquire test, focused race suite, full
+aggregate command, and portable no-runtime packages all pass. Measurement:
+`docs/evals/2026-08-13-onnx-runtime-lifecycle.md`.