docs(contract): close output-contract gaps — mode/manualDemand, Port-2 topic, output manifest

- wiki/Reference-Contracts.md: regenerate data-model (npm run wiki:all) so the
  two live getOutput() keys `mode` and `manualDemand` are documented; refresh
  stale sample values; bump code-ref badge -> a83a85e; add human note describing
  the two control-state keys.
- CONTRACT.md: fix Port-2 outgoing topic registerChild -> child.register
  (registerChild is the deprecated *input* alias, not what the node emits).
- test/_output-manifest.md: add the mandatory output manifest (Port 0/1/2 +
  emitter events + the 15-way fn_status_split fan-out) with honest coverage gaps.
- test/integration/basic-dashboard-flow.test.js: fix stale fan-out count 14->15
  (output 14 = percControl chart added upstream); assert out[14].

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CONTRACT.md

@@ -25,8 +25,9 @@ Aliases log a one-time deprecation warning the first time they fire.
 - **Port 1 (InfluxDB telemetry):** same shape as Port 0, formatted with the
   `'influxdb'` formatter.
 - **Port 2 (registration):** at startup the node sends one
-  `{ topic: 'registerChild', payload: <node.id>, positionVsParent, distance }`
-  to the upstream parent.
+  `{ topic: 'child.register', payload: <node.id>, positionVsParent, distance }`
+  to the upstream parent (`child.register` is canonical; `registerChild` is the
+  deprecated *input* alias, not what this node emits).
 
 ## Events emitted by `source.measurements.emitter`