P6: convert monster to BaseDomain + BaseNodeAdapter + concern split

Refactor of monster to use the platform infrastructure (BaseDomain, BaseNodeAdapter,
ChildRouter, commandRegistry, statusBadge). Extracts concerns into
focused modules per .claude/refactor/MODULE_SPLIT.md generic template.
Tests stay green; CONTRACT.md generated; legacy aliases preserved.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/flow/flowTracker.js

@@ -0,0 +1,59 @@
+'use strict';
+
+// Flow tracking — manual override + measured-child fan-in + effective
+// blend (mean of the two when both present). Wraps the
+// MeasurementContainer so the domain stays read-only on flow state.
+
+const POSITIONS = ['upstream', 'downstream', 'atequipment'];
+
+class FlowTracker {
+  constructor({ measurements, logger }) {
+    this.measurements = measurements;
+    this.logger = logger;
+    this.manualFlow = null;
+  }
+
+  updateManualFlow(payload = {}) {
+    const value = Number(payload.value);
+    if (!Number.isFinite(value)) return;
+    const unit = payload.unit || 'm3/h';
+    this.manualFlow = value;
+    this.measurements.type('flow').variant('manual').position('atequipment')
+      .value(value, Date.now(), unit);
+  }
+
+  handleMeasuredFlow(eventData) {
+    const value = Number(eventData?.value);
+    if (!Number.isFinite(value)) return;
+    const position = String(eventData.position || 'atequipment').toLowerCase();
+    const unit = eventData.unit || 'm3/h';
+    this.measurements.type('flow').variant('measured').position(position)
+      .value(value, eventData.timestamp || Date.now(), unit);
+  }
+
+  getMeasuredFlow() {
+    const values = [];
+    for (const pos of POSITIONS) {
+      const v = this.measurements.type('flow').variant('measured').position(pos).getCurrentValue();
+      if (Number.isFinite(v)) values.push(v);
+    }
+    if (!values.length) return null;
+    return values.reduce((s, c) => s + c, 0) / values.length;
+  }
+
+  getManualFlow() {
+    const v = this.measurements.type('flow').variant('manual').position('atequipment').getCurrentValue();
+    return Number.isFinite(v) ? v : null;
+  }
+
+  getEffectiveFlow() {
+    const measured = this.getMeasuredFlow();
+    const manual = this.getManualFlow();
+    if (measured != null && manual != null) return (measured + manual) / 2;
+    if (measured != null) return measured;
+    if (manual != null) return manual;
+    return 0;
+  }
+}
+
+module.exports = FlowTracker;