feat(subagent): deliver continuable child settlement to parents

A continuable child that stopped without reporting — an error, a token
ceiling, cancellation, teardown — left its parent nothing to act on.
The continuation manager now delivers an unconditional settlement
notice to the durable direct parent before releasing ownership, folding
consumed work (foldConsumedWork supersedes findLastMessageTurnEnd) so a
claimed-but-unrun prompt reads as aborted rather than completed, waking
an idle parent, steering a busy one, and never waking a closing tree.

examples/acp-agent/subagent-report-quiet.cordis.yml

@@ -0,0 +1,17 @@
+# Snapshot-only overlay pinning quiet report delivery. The shipped default wakes
+# the parent on every accepted report, and the runtime's settlement notice wakes
+# it again when the child's Activation ends; two independent wakes have no single
+# authored order. Quiet delivery leaves settlement as the only wake, while the
+# fixture below holds the child until the parent's spawn turn has closed.
+- id: base
+  name: '@deepseek-ai/cordis-plugin-include'
+  config:
+    path: ./cordis.yml
+    patches:
+      - id: tool-subagent-report
+        name: '@deepseek-ai/dsh-tool-subagent-report'
+        config:
+          reportDelivery: quiet
+
+- id: report-fence
+  name: './tests/fixtures/subagent-report-fence.ts'