Hold-then-ramp shift semantics + shiftArmPercent + e2e tests

Runtime (specificClass.js):
- Replace the "shift left both ramp ends" geometry with a true
  hold-then-ramp hysteresis driven by output %, not level:
  • Up-curve % crosses shiftArmPercent on the way up → ARM.
  • Filling→draining transition while armed → capture the up-curve %
    at that moment as _shiftHoldValue.
  • Draining + level ≥ shiftLevel → output stays at _shiftHoldValue
    (horizontal hold, matching the dashed segment in the SVG).
  • Draining + level in [start, shift] → output ramps holdValue → 0 %
    along the same curve shape (linear or log) as the up curve.
  • Draining + level < startLevel → 0 % AND disarm.
  • Returning to filling clears holdValue, stays armed; next drain
    transition captures a fresh hold so bouncing fills rearm cleanly.
  • Disarm only when level ≤ startLevel.
- New _curveShape(x) helper for shared linear/log shaping.
- Removed legacy _levelBasedRampStart / _levelBasedRampTop /
  _updateShiftArmed in favour of the inline state machine.

Adapter (nodeClass.js):
- Pipe shiftArmPercent through to control.levelbased.

Editor (pumpingStation.html + src/editor/):
- Add shiftArmPercent input row (% with unit) to the mode side panel
  (only shown when shifted ramp is enabled). Default 95 %.
- Add the horizontal arming-% line + label inside the mode SVG —
  this is the "% Threshold triggering shifted ramp down" line from
  the original drawing that had been missing.
- Redraw the shifted-down curve to match the SVG geometry literally:
  100 % flat from maxLevel → shiftLevel, then ramp shiftLevel →
  startLevel down to 0 %, OFF below startLevel. Preview shows the
  worst-case envelope (hold = 100 %); runtime hold is captured live.
- Validation extended: 0 < shiftArmPercent ≤ 100; ordering rules
  preserved (start < shift ≤ max etc.).
- Auto-default shiftArmPercent to 95 when shift is enabled and the
  current value is missing or out of range.

Dashboard example (examples/basic-dashboard.flow.json):
- Parser now reads `level.predicted.atequipment.default` etc. The
  MeasurementContainer flatten format includes the implicit 'default'
  childId; consumers must include it. Comment in the parser points
  at the documenting source in generalFunctions.

Tests:
- test/basic: replace old level-armed-shift tests with two new ones
  that exercise the hold-then-ramp arming, capture, hold, ramp-down,
  disarm, and the bounce case (filling→draining→filling→draining
  captures a fresh hold each time).
- test/integration/shifted-ramp-end-to-end.test.js: new file. Drives
  Q_IN/Q_OUT through the full runtime tick with a controllable clock,
  asserting the same hysteresis path the dashboard exercises.
- test/integration/basic-dashboard-flow.test.js: fixture keys updated
  to the .default-suffixed form so they match the real flatten output.
56/56 tests pass.

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

src/editor/oneditprepare.js

@@ -68,6 +68,7 @@
     ns.setNumberField('node-input-maxLevel',       node.maxLevel);
     ns.setNumberField('node-input-logCurveFactor', node.logCurveFactor);
     ns.setNumberField('node-input-shiftLevel',     node.shiftLevel);
+    ns.setNumberField('node-input-shiftArmPercent', Number.isFinite(node.shiftArmPercent) ? node.shiftArmPercent : 95);
     ns.setNumberField('node-input-flowSetpoint',   node.flowSetpoint);
     ns.setNumberField('node-input-flowDeadband',   node.flowDeadband);
 
@@ -87,7 +88,8 @@
       // so the mode preview must redraw when either of those change.
       ['startLevel', 'maxLevel', 'inflowLevel', 'outflowLevel', 'overflowLevel',
        'dryRunThresholdPercent',
-       'levelCurveType', 'logCurveFactor', 'enableShiftedRamp', 'shiftLevel'],
+       'levelCurveType', 'logCurveFactor', 'enableShiftedRamp', 'shiftLevel',
+       'shiftArmPercent'],
       ns.modePreview.redraw
     );