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>

test/basic/BasinGeometry.basic.test.js

@@ -0,0 +1,106 @@
+// Basic unit tests for BasinGeometry.
+// Run with:  node --test test/basic/BasinGeometry.basic.test.js
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const BasinGeometry = require('../../src/basin/BasinGeometry');
+
+function makeBasin(overrides = {}) {
+  const basin = {
+    volume: 50,
+    height: 5,
+    inflowLevel: 3,
+    outflowLevel: 0.2,
+    overflowLevel: 4.5,
+    ...overrides.basin,
+  };
+  const hydraulics = {
+    minHeightBasedOn: 'outlet',
+    ...overrides.hydraulics,
+  };
+  return new BasinGeometry(basin, hydraulics);
+}
+
+test('constructor produces correct surfaceArea = volume / height', () => {
+  const g = makeBasin();
+  assert.equal(g.surfaceArea, 10);  // 50 / 5
+  assert.equal(g.heightBasin, 5);
+  assert.equal(g.volEmptyBasin, 50);
+});
+
+test('maxVolAtOverflow equals overflowLevel × surfaceArea', () => {
+  const g = makeBasin();
+  assert.equal(g.maxVolAtOverflow, 4.5 * 10);  // 45
+  assert.equal(g.minVolAtInflow, 3 * 10);       // 30
+  assert.equal(g.minVolAtOutflow, 0.2 * 10);    // 2
+  assert.equal(g.maxVol, 50);
+});
+
+test("minVol selects outlet-based when minHeightBasedOn = 'outlet'", () => {
+  const g = makeBasin();
+  assert.equal(g.minVol, g.minVolAtOutflow);
+  assert.equal(g.minHeightBasedOn, 'outlet');
+});
+
+test("minVol selects inlet-based when minHeightBasedOn = 'inlet'", () => {
+  const g = makeBasin({ hydraulics: { minHeightBasedOn: 'inlet' } });
+  assert.equal(g.minVol, g.minVolAtInflow);
+  assert.equal(g.minHeightBasedOn, 'inlet');
+});
+
+test('volumeFromLevel(0) returns 0; negative level clamps to 0', () => {
+  const g = makeBasin();
+  assert.equal(g.volumeFromLevel(0), 0);
+  assert.equal(g.volumeFromLevel(-1), 0);
+  assert.equal(g.volumeFromLevel(-1e9), 0);
+});
+
+test('volumeFromLevel(positive) is level × surfaceArea', () => {
+  const g = makeBasin();
+  assert.equal(g.volumeFromLevel(2.5), 25);
+  assert.equal(g.volumeFromLevel(5), 50);
+});
+
+test('levelFromVolume(maxVol) returns heightBasin', () => {
+  const g = makeBasin();
+  assert.equal(g.levelFromVolume(g.maxVol), g.heightBasin);
+});
+
+test('levelFromVolume(0) returns 0; negative volume clamps to 0', () => {
+  const g = makeBasin();
+  assert.equal(g.levelFromVolume(0), 0);
+  assert.equal(g.levelFromVolume(-10), 0);
+});
+
+test('round-trip: volumeFromLevel(levelFromVolume(v)) ≈ v for v in range', () => {
+  const g = makeBasin();
+  for (const v of [0, 0.001, 1, 12.34, 25, 49.999, 50]) {
+    const back = g.volumeFromLevel(g.levelFromVolume(v));
+    assert.ok(Math.abs(back - v) < 1e-9, `round-trip failed for v=${v}, got ${back}`);
+  }
+});
+
+test('round-trip: levelFromVolume(volumeFromLevel(L)) ≈ L for L in range', () => {
+  const g = makeBasin();
+  for (const L of [0, 0.05, 1, 2.5, 4.5, 5]) {
+    const back = g.levelFromVolume(g.volumeFromLevel(L));
+    assert.ok(Math.abs(back - L) < 1e-9, `round-trip failed for L=${L}, got ${back}`);
+  }
+});
+
+test('snapshot() exposes legacy this.basin field names', () => {
+  const g = makeBasin();
+  const s = g.snapshot();
+  const expectedKeys = [
+    'volEmptyBasin', 'heightBasin', 'inflowLevel', 'outflowLevel',
+    'overflowLevel', 'surfaceArea', 'maxVol', 'maxVolAtOverflow',
+    'minVolAtInflow', 'minVolAtOutflow', 'minVol', 'minHeightBasedOn',
+  ];
+  for (const k of expectedKeys) {
+    assert.ok(k in s, `snapshot missing key: ${k}`);
+  }
+  assert.equal(s.volEmptyBasin, 50);
+  assert.equal(s.surfaceArea, 10);
+  assert.equal(s.minHeightBasedOn, 'outlet');
+});