fix(charts): add all required FlowFuse ui-chart properties + document in rule set

Charts rendered blank because the helper was missing 15+ required
FlowFuse properties. The critical three:
  - interpolation: "linear" (no line drawn without it)
  - yAxisProperty: "payload" + yAxisPropertyType: "msg" (chart didn't
    know which msg field to plot)
  - xAxisPropertyType: "timestamp" (chart didn't know the x source)

Also: width/height must be numbers not strings, colors/textColor/
gridColor arrays must be present, and stackSeries/bins/xAxisFormat/
xAxisFormatType all need explicit values.

Fixed the ui_chart helper to include every property from the working
rotatingMachine/examples/03-Dashboard.json charts. Added the full
required-property template + gotcha list to the flow-layout rule set
(Section 4) so this class of bug is caught by reference on the next
chart build.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

examples/pumpingstation-3pumps-dashboard/build_flow.py

@@ -258,32 +258,65 @@ def ui_switch(node_id, tab, x, y, group, name, label, on_value, off_value,
 
 
 def ui_chart(node_id, tab, x, y, group, name, label,
-             width="12", height="6",
-             remove_older="10", remove_older_unit="60",
-             remove_older_points="200",
-             ymin=None, ymax=None, order=1):
+             width=12, height=6,
+             remove_older="15", remove_older_unit="60",
+             remove_older_points="",
+             y_axis_label="", ymin=None, ymax=None, order=1):
     """
-    FlowFuse ui-chart. Dimensions are in grid units:
-      width="12"  = full group width
-      height="6"  = about 300 px tall
-    `remove_older` + `remove_older_unit` define the rolling window
-    (e.g. "10" + "60" = 10 minutes). `remove_older_points` caps points
-    per series.
+    FlowFuse ui-chart (line type, time x-axis).
+
+    IMPORTANT: This template is derived from the working charts in
+    rotatingMachine/examples/03-Dashboard.json. Every field listed below
+    is required or the chart renders blank. Key gotchas:
+
+      - `width` / `height` must be NUMBERS not strings.
+      - `interpolation` must be set ("linear", "step", "bezier",
+        "cubic", "cubic-mono") or no line is drawn.
+      - `yAxisProperty: "payload"` + `yAxisPropertyType: "msg"` tells
+        the chart WHERE in the msg to find the y-value. Without these
+        the chart has no data to plot.
+      - `xAxisPropertyType: "timestamp"` tells the chart to use
+        msg.timestamp (or auto-generated timestamp) for the x-axis.
+      - `removeOlderPoints` should be "" (empty string) to let
+        removeOlder + removeOlderUnit control retention, OR a number
+        string to cap points per series.
     """
     return {
         "id": node_id, "type": "ui-chart", "z": tab, "group": group,
-        "name": name, "label": label, "order": order, "chartType": "line",
+        "name": name, "label": label, "order": order,
+        "chartType": "line",
+        "interpolation": "linear",
+        # Series identification
         "category": "topic", "categoryType": "msg",
-        "xAxisLabel": "", "xAxisType": "time", "xAxisTimeFormat": "auto",
-        "yAxisLabel": "", "ymin": "" if ymin is None else str(ymin),
+        # X-axis (time)
+        "xAxisLabel": "", "xAxisType": "time",
+        "xAxisProperty": "", "xAxisPropertyType": "timestamp",
+        "xAxisFormat": "", "xAxisFormatType": "auto",
+        "xmin": "", "xmax": "",
+        # Y-axis (msg.payload)
+        "yAxisLabel": y_axis_label,
+        "yAxisProperty": "payload", "yAxisPropertyType": "msg",
+        "ymin": "" if ymin is None else str(ymin),
         "ymax": "" if ymax is None else str(ymax),
-        "action": "append", "pointShape": "circle", "pointRadius": 2,
-        "showLegend": True,
+        # Data retention
         "removeOlder": str(remove_older),
         "removeOlderUnit": str(remove_older_unit),
         "removeOlderPoints": str(remove_older_points),
-        "colors": [], "textColor": [], "textColorDefault": True,
-        "width": str(width), "height": str(height), "className": "",
+        # Rendering
+        "action": "append",
+        "stackSeries": False,
+        "pointShape": "circle", "pointRadius": 4,
+        "showLegend": True,
+        "bins": 10,
+        # Colours (defaults — chart auto-cycles through these per series)
+        "colors": [
+            "#0095FF", "#FF0000", "#FF7F0E", "#2CA02C",
+            "#A347E1", "#D62728", "#FF9896", "#9467BD", "#C5B0D5",
+        ],
+        "textColor": ["#666666"], "textColorDefault": True,
+        "gridColor": ["#e5e5e5"], "gridColorDefault": True,
+        # Editor layout + dimensions (NUMBERS, not strings)
+        "width": int(width), "height": int(height), "className": "",
         "x": x, "y": y,
         "wires": [[]],
     }