feat(dashboard): add tank gauge for basin level + 270° arc for fill %

Basin Status group on the Control page now has two visual gauges:

1. gauge-tank (vertical tank with fill gradient) for basin level 0–3 m.
   Color zones: red < 0.6 m (below stopLevel) → orange → blue 1.2–2.5 m
   (normal operating range) → orange → red > 2.8 m (overflow zone).

2. gauge-34 (270° arc) for fill percentage 0–100%.
   Color zones: red < 10% → orange → green 30–80% → orange → red > 95%.

Both gauges are fed from the PS dispatcher's numeric outputs (fillPctNum
and levelNum) which also feed the basin trend charts — same data, two
visual forms.

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

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

@@ -905,13 +905,54 @@ def build_ui_tab():
             ["ui_ps_netflow"],
             ["ui_ps_timeleft"],
             ["ui_ps_qin"],
-            # Trend outputs → both short + long charts
-            ["trend_short_basin", "trend_long_basin"],     # fill %
-            ["trend_short_basin", "trend_long_basin"],     # level
-            ["trend_short_basin", "trend_long_basin"],     # net flow
+            # Trend + gauge outputs
+            ["trend_short_basin", "trend_long_basin", "gauge_ps_fill"],   # fill % → charts + gauge
+            ["trend_short_basin", "trend_long_basin", "gauge_ps_level"],  # level → charts + tank gauge
+            ["trend_short_basin", "trend_long_basin"],                     # net flow → charts only
         ],
     ))
 
+    # PS gauges — tank for level, 270° arc for fill %
+    # Tank gauge: basin level 0 – 3 m with color zones matching
+    # startLevel (1.2 m) and stopLevel (0.6 m).
+    nodes.append({
+        "id": "gauge_ps_level", "type": "ui-gauge", "z": TAB_UI,
+        "group": g_ps, "name": "Basin level gauge",
+        "gtype": "gauge-tank", "gstyle": "Rounded",
+        "title": "Basin Level", "units": "m",
+        "prefix": "", "suffix": " m",
+        "min": 0, "max": 3,
+        "segments": [
+            {"color": "#f44336", "from": 0},       # red: below stopLevel
+            {"color": "#ff9800", "from": 0.6},      # orange: between stop and start
+            {"color": "#2196f3", "from": 1.2},      # blue: normal operating range
+            {"color": "#ff9800", "from": 2.5},      # orange: approaching overflow
+            {"color": "#f44336", "from": 2.8},       # red: overflow zone
+        ],
+        "width": 3, "height": 5, "order": 1,
+        "icon": "", "sizeGauge": 20, "sizeGap": 2, "sizeSegments": 10,
+        "x": LANE_X[3], "y": y + 160, "wires": [],
+    })
+    # 270° arc: fill percentage 0–100%
+    nodes.append({
+        "id": "gauge_ps_fill", "type": "ui-gauge", "z": TAB_UI,
+        "group": g_ps, "name": "Basin fill gauge",
+        "gtype": "gauge-34", "gstyle": "Rounded",
+        "title": "Fill", "units": "%",
+        "prefix": "", "suffix": "%",
+        "min": 0, "max": 100,
+        "segments": [
+            {"color": "#f44336", "from": 0},       # red: dangerously low
+            {"color": "#ff9800", "from": 10},       # orange: low
+            {"color": "#4caf50", "from": 30},       # green: normal
+            {"color": "#ff9800", "from": 80},       # orange: getting full
+            {"color": "#f44336", "from": 95},       # red: near overflow
+        ],
+        "width": 3, "height": 4, "order": 2,
+        "icon": "water_drop", "sizeGauge": 20, "sizeGap": 2, "sizeSegments": 10,
+        "x": LANE_X[4], "y": y + 160, "wires": [],
+    })
+
     # PS text widgets
     nodes.append(ui_text("ui_ps_direction", TAB_UI, LANE_X[2], y + 160, g_ps,
                         "PS direction", "Direction",    "{{msg.payload}}"))