P2 wave 1: extract concerns from pumpingStation specificClass

Splits pumpingStation/src/ into focused concern modules. specificClass.js
will be slimmed to an orchestrator in P2.9 (integration); for now both
the inlined logic AND the new modules coexist so tests stay green
throughout.

  src/basin/         BasinGeometry + thresholdValidator (pure)
  src/measurement/   flowAggregator + measurementRouter + calibration
  src/control/       levelBased + flowBased(stub) + manual + index dispatcher
  src/safety/        safetyController split into dryRun + overfill rules
  src/commands/      registry array + handlers (canonical names from start)
  src/editor.js      260 lines of SVG basin-diagram redraw, was inline in .html
  examples/standalone-demo.js  was if(require.main===module) at bottom of specificClass.js
  CONTRACT.md        canonical inputs + outputs + emitted events

Modified:
  src/specificClass.js  removed the 170-line standalone demo block
  pumpingStation.html   oneditprepare/oneditsave delegate to editor.{init,save}
  pumpingStation.js     added admin endpoint serving src/editor.js

102 basic tests pass (60 new + 42 existing).
specificClass.js itself is unchanged in behaviour — integration is P2.9.

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

src/basin/BasinGeometry.js

@@ -0,0 +1,91 @@
+// Basin geometry for a wet-well pumping station.
+//
+// Models the basin as a rectangular prism (constant cross-section), so
+// volume = level × surfaceArea. Owns the level↔volume conversions and the
+// derived threshold volumes used by control + safety. Pure domain — no
+// Node-RED, no logger, no side effects beyond construction.
+
+class BasinGeometry {
+  /**
+   * @param {object} basinConfig - { volume, height, inflowLevel, outflowLevel, overflowLevel }
+   * @param {object} hydraulicsConfig - { minHeightBasedOn: 'inlet' | 'outlet' }
+   */
+  constructor(basinConfig, hydraulicsConfig) {
+    const volEmptyBasin = basinConfig.volume;
+    const heightBasin = basinConfig.height;
+    const inflowLevel = basinConfig.inflowLevel;
+    const outflowLevel = basinConfig.outflowLevel;
+    const overflowLevel = basinConfig.overflowLevel;
+    const minHeightBasedOn = hydraulicsConfig?.minHeightBasedOn;
+
+    const surfaceArea = volEmptyBasin / heightBasin;
+
+    // maxVol ≡ volEmptyBasin under the constant cross-section assumption;
+    // kept as a separate field for naming symmetry with the trigger volumes.
+    const maxVol = heightBasin * surfaceArea;
+    const maxVolAtOverflow = overflowLevel * surfaceArea;
+    const minVolAtOutflow = outflowLevel * surfaceArea;
+    const minVolAtInflow = inflowLevel * surfaceArea;
+    const minVol = minHeightBasedOn === 'inlet' ? minVolAtInflow : minVolAtOutflow;
+
+    this._volEmptyBasin = volEmptyBasin;
+    this._heightBasin = heightBasin;
+    this._inflowLevel = inflowLevel;
+    this._outflowLevel = outflowLevel;
+    this._overflowLevel = overflowLevel;
+    this._surfaceArea = surfaceArea;
+    this._maxVol = maxVol;
+    this._maxVolAtOverflow = maxVolAtOverflow;
+    this._minVolAtInflow = minVolAtInflow;
+    this._minVolAtOutflow = minVolAtOutflow;
+    this._minVol = minVol;
+    this._minHeightBasedOn = minHeightBasedOn;
+  }
+
+  get volEmptyBasin()    { return this._volEmptyBasin; }
+  get heightBasin()      { return this._heightBasin; }
+  get inflowLevel()      { return this._inflowLevel; }
+  get outflowLevel()     { return this._outflowLevel; }
+  get overflowLevel()    { return this._overflowLevel; }
+  get surfaceArea()      { return this._surfaceArea; }
+  get maxVol()           { return this._maxVol; }
+  get maxVolAtOverflow() { return this._maxVolAtOverflow; }
+  get minVolAtInflow()   { return this._minVolAtInflow; }
+  get minVolAtOutflow()  { return this._minVolAtOutflow; }
+  get minVol()           { return this._minVol; }
+  get minHeightBasedOn() { return this._minHeightBasedOn; }
+
+  /** Convert level (m from floor) → volume (m3). Negative levels clamp to 0. */
+  volumeFromLevel(level) {
+    return Math.max(level, 0) * this._surfaceArea;
+  }
+
+  /** Convert volume (m3) → level (m from floor). Negative volumes clamp to 0. */
+  levelFromVolume(volume) {
+    return Math.max(volume, 0) / this._surfaceArea;
+  }
+
+  /**
+   * Plain-object snapshot mirroring the legacy `this.basin` shape so
+   * getOutput / status code can keep using the same field names without
+   * caring whether it's holding a class instance or a plain object.
+   */
+  snapshot() {
+    return {
+      volEmptyBasin: this._volEmptyBasin,
+      heightBasin: this._heightBasin,
+      inflowLevel: this._inflowLevel,
+      outflowLevel: this._outflowLevel,
+      overflowLevel: this._overflowLevel,
+      surfaceArea: this._surfaceArea,
+      maxVol: this._maxVol,
+      maxVolAtOverflow: this._maxVolAtOverflow,
+      minVolAtInflow: this._minVolAtInflow,
+      minVolAtOutflow: this._minVolAtOutflow,
+      minVol: this._minVol,
+      minHeightBasedOn: this._minHeightBasedOn,
+    };
+  }
+}
+
+module.exports = BasinGeometry;