fix(ps): persist stopLevel/holdLevel as numbers across editor save

Node-RED's auto-form-binding writes <input type="number"> values into the
node object as strings. The editor's setNumberField helper used strict
Number.isFinite(val) which rejects "0.5" and blanked the input on reopen,
so users saw their stopLevel/holdLevel values disappear after clicking Done.

- oneditsave: explicitly parseFloat stopLevel, holdLevel, and
  deadZoneKeepAlivePercent so they land in the node as numbers (matches the
  treatment of startLevel/maxLevel).
- oneditprepare: parseFloat node.holdLevel / node.deadZoneKeepAlivePercent
  before the Number.isFinite check so existing string-typed flows still
  render their saved values.
- index.js setNumberField: defensively coerce stringy numbers so this
  gotcha can't bite a future field.

Verified end-to-end in headless Chromium: type new values, click Done,
reopen — values persist and the stopLevel/holdLevel marker lines render
at the correct x in the level-based mode preview.

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

src/editor/index.js

@@ -11,10 +11,13 @@
     return Number.isFinite(v) ? v : null;
   };
 
-  // Set a numeric input's value, or blank if not finite.
+  // Set a numeric input's value, or blank if not finite. Accepts numeric
+  // strings (Node-RED's auto-form-binding stores form values as strings).
   ns.setNumberField = (id, val) => {
     const el = document.getElementById(id);
-    if (el) el.value = Number.isFinite(val) ? val : '';
+    if (!el) return;
+    const num = typeof val === 'number' ? val : parseFloat(val);
+    el.value = Number.isFinite(num) ? num : '';
   };
 
   // Add input + change listeners to a list of node-input-* ids.

src/editor/oneditprepare.js

@@ -68,11 +68,14 @@
     ns.setNumberField('node-input-stopLevel',      node.stopLevel);
     // holdLevel defaults to startLevel when omitted (no hold band). Show
     // the saved value if there is one; otherwise mirror startLevel so the
-    // user immediately sees the "no hold band" baseline.
+    // user immediately sees the "no hold band" baseline. Coerce to Number
+    // because Node-RED form-bind stores numeric inputs as strings.
+    const holdNum = parseFloat(node.holdLevel);
     ns.setNumberField('node-input-holdLevel',
-      Number.isFinite(node.holdLevel) ? node.holdLevel : node.startLevel);
+      Number.isFinite(holdNum) ? holdNum : node.startLevel);
+    const deadZoneNum = parseFloat(node.deadZoneKeepAlivePercent);
     ns.setNumberField('node-input-deadZoneKeepAlivePercent',
-      Number.isFinite(node.deadZoneKeepAlivePercent) ? node.deadZoneKeepAlivePercent : 1);
+      Number.isFinite(deadZoneNum) ? deadZoneNum : 1);
     ns.setNumberField('node-input-maxLevel',       node.maxLevel);
     ns.setNumberField('node-input-logCurveFactor', node.logCurveFactor);
     ns.setNumberField('node-input-shiftLevel',     node.shiftLevel);

src/editor/oneditsave.js

@@ -50,6 +50,15 @@
     node.logCurveFactor = parseNum('node-input-logCurveFactor');
     node.startLevel = parseNum('node-input-startLevel');
     node.maxLevel = parseNum('node-input-maxLevel');
+    // Persist as numbers — Node-RED's auto-form-binding would store these as
+    // strings, and oneditprepare's setNumberField rejects non-Number values,
+    // so the input would blank out on reopen.
+    const stopLevelVal = parseNum('node-input-stopLevel');
+    node.stopLevel = Number.isFinite(stopLevelVal) ? stopLevelVal : null;
+    const holdLevelVal = parseNum('node-input-holdLevel');
+    if (Number.isFinite(holdLevelVal)) node.holdLevel = holdLevelVal;
+    const deadZoneVal = parseNum('node-input-deadZoneKeepAlivePercent');
+    if (Number.isFinite(deadZoneVal)) node.deadZoneKeepAlivePercent = deadZoneVal;
     // minLevel is no longer a user input — it's the derived dryRunLevel
     // (outflowLevel × (1 + dryRunThresholdPercent/100)). The runtime still
     // uses node.minLevel as the unconditional STOP threshold; we set it