feat(ui/triggers): expression trigger panel in the script & alarm editors

src/ScadaLink.CentralUI/Components/Shared/ScriptTriggerEditor.razor

@@ -23,6 +23,7 @@
             <option value="Interval">Interval — run on a fixed timer</option>
             <option value="ValueChange">Value change — run when an attribute changes</option>
             <option value="Conditional">Conditional — run when a condition is met</option>
+            <option value="Expression">Expression — run when a boolean expression becomes true</option>
             <option value="Call">Call — run only when invoked by another script</option>
             @if (_kind == ScriptTriggerKind.Unknown)
             {
@@ -45,6 +46,9 @@
         case ScriptTriggerKind.Conditional:
             @RenderConditional();
             break;
+        case ScriptTriggerKind.Expression:
+            @RenderExpression();
+            break;
         case ScriptTriggerKind.Call:
             <div class="small text-muted">
                 No automatic trigger — this script runs only when another script
@@ -62,7 +66,8 @@
     }
 
     @* ── Hint ──────────────────────────────────────────────────────────── *@
-    @if (_kind is ScriptTriggerKind.Interval or ScriptTriggerKind.ValueChange or ScriptTriggerKind.Conditional)
+    @if (_kind is ScriptTriggerKind.Interval or ScriptTriggerKind.ValueChange
+         or ScriptTriggerKind.Conditional or ScriptTriggerKind.Expression)
     {
         <div class="mt-3 pt-2 border-top small text-muted">@BuildHint()</div>
     }
@@ -244,6 +249,30 @@
         await Emit();
     }
 
+    // ── Expression ─────────────────────────────────────────────────────────
+
+    private RenderFragment RenderExpression() => __builder =>
+    {
+        <label class="form-label small text-uppercase text-muted fw-semibold mb-1">Trigger expression</label>
+        <MonacoEditor Height="120px"
+                      Language="csharp"
+                      ScriptKind="ScriptAnalysis.ScriptKind.Template"
+                      ShowToolbar="false"
+                      Value="@(_model.Expression ?? string.Empty)"
+                      ValueChanged="OnExpressionChanged"
+                      SelfAttributes="@TriggerAttributeMapper.SelfAttributes(AvailableAttributes)"
+                      Children="@TriggerAttributeMapper.Children(AvailableAttributes)" />
+        <div class="form-text">
+            A boolean C# expression — e.g. <code>Attributes["Temperature"] &gt; 80</code>.
+        </div>
+    };
+
+    private async Task OnExpressionChanged(string value)
+    {
+        _model.Expression = value;
+        await Emit();
+    }
+
     // ── Attribute picker (ValueChange + Conditional) ───────────────────────
 
     private RenderFragment RenderAttributePicker(string label) => __builder =>
@@ -315,6 +344,9 @@
                     ? $"Runs when {attr} changes, if {attr} {_model.Operator} {t.ToString("0.###", CultureInfo.InvariantCulture)}."
                     : $"Runs when {attr} changes and meets the configured condition — set a threshold above.",
 
+            ScriptTriggerKind.Expression =>
+                "Runs once each time this expression becomes true.",
+
             _ => string.Empty
         };
     }