feat(ui): structured editors for script schemas and alarm triggers

Replace raw-JSON text inputs with rich UI: script parameter/return types use
a JSON Schema builder (SchemaBuilder + JsonSchemaShapeParser, with a migration
to convert existing definitions); alarm trigger config uses a type-aware
editor with a flattened attribute picker (AlarmTriggerEditor). AlarmActor
gains optional direction (rising/falling/either) on RateOfChange triggers.

tests/ScadaLink.CentralUI.Tests/Shared/SchemaBuilderModelTests.cs

@@ -0,0 +1,141 @@
+using ScadaLink.CentralUI.Components.Shared;
+
+namespace ScadaLink.CentralUI.Tests.Shared;
+
+public class SchemaBuilderModelTests
+{
+    // ── Parse ─────────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Parse_Empty_ReturnsFallback()
+    {
+        var fallback = SchemaBuilderModel.NewObject();
+        Assert.Same(fallback, SchemaBuilderModel.Parse(null, fallback));
+        Assert.Same(fallback, SchemaBuilderModel.Parse("", fallback));
+        Assert.Same(fallback, SchemaBuilderModel.Parse("   ", fallback));
+    }
+
+    [Fact]
+    public void Parse_Malformed_ReturnsFallback()
+    {
+        var fallback = SchemaBuilderModel.NewObject();
+        Assert.Same(fallback, SchemaBuilderModel.Parse("{not json", fallback));
+        Assert.Same(fallback, SchemaBuilderModel.Parse("42", fallback));
+    }
+
+    [Fact]
+    public void Parse_ObjectSchema_ExtractsPropertiesAndRequired()
+    {
+        const string json = """
+            {"type":"object","properties":{
+              "id":{"type":"integer"},
+              "label":{"type":"string"},
+              "active":{"type":"boolean"}
+            },"required":["id","active"]}
+            """;
+        var node = SchemaBuilderModel.Parse(json, SchemaBuilderModel.NewObject());
+
+        Assert.Equal("object", node.Type);
+        Assert.Collection(node.Properties,
+            p => { Assert.Equal("id", p.Name); Assert.Equal("integer", p.Schema.Type); Assert.True(p.Required); },
+            p => { Assert.Equal("label", p.Name); Assert.Equal("string", p.Schema.Type); Assert.False(p.Required); },
+            p => { Assert.Equal("active", p.Name); Assert.Equal("boolean", p.Schema.Type); Assert.True(p.Required); });
+    }
+
+    [Fact]
+    public void Parse_ArrayOfPrimitive_PreservesItemType()
+    {
+        var node = SchemaBuilderModel.Parse(
+            @"{""type"":""array"",""items"":{""type"":""integer""}}",
+            SchemaBuilderModel.NewValue());
+
+        Assert.Equal("array", node.Type);
+        Assert.NotNull(node.Items);
+        Assert.Equal("integer", node.Items!.Type);
+    }
+
+    [Fact]
+    public void Parse_LegacyFlatArray_TranslatedToObjectSchema()
+    {
+        const string json = """[{"name":"x","type":"Integer"},{"name":"y","type":"String","required":false}]""";
+        var node = SchemaBuilderModel.Parse(json, SchemaBuilderModel.NewObject());
+
+        Assert.Equal("object", node.Type);
+        Assert.Collection(node.Properties,
+            p => { Assert.Equal("x", p.Name); Assert.Equal("integer", p.Schema.Type); Assert.True(p.Required); },
+            p => { Assert.Equal("y", p.Name); Assert.Equal("string", p.Schema.Type); Assert.False(p.Required); });
+    }
+
+    [Fact]
+    public void Parse_NestedObjects_Recurses()
+    {
+        const string json = """
+            {"type":"object","properties":{
+              "outer":{"type":"object","properties":{
+                "inner":{"type":"integer"}
+              },"required":["inner"]}
+            }}
+            """;
+        var node = SchemaBuilderModel.Parse(json, SchemaBuilderModel.NewObject());
+
+        var outer = Assert.Single(node.Properties);
+        Assert.Equal("outer", outer.Name);
+        Assert.Equal("object", outer.Schema.Type);
+        var inner = Assert.Single(outer.Schema.Properties);
+        Assert.Equal("inner", inner.Name);
+        Assert.Equal("integer", inner.Schema.Type);
+        Assert.True(inner.Required);
+    }
+
+    // ── Serialize ─────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Serialize_EmptyObject_OmitsRequired()
+    {
+        var node = new SchemaNode { Type = "object" };
+        var json = SchemaBuilderModel.Serialize(node);
+        Assert.Equal("""{"type":"object","properties":{}}""", json);
+    }
+
+    [Fact]
+    public void Serialize_ObjectWithMixedRequired_EmitsOnlyRequiredNames()
+    {
+        var node = new SchemaNode { Type = "object" };
+        node.Properties.Add(new SchemaProperty { Name = "id", Required = true, Schema = new SchemaNode { Type = "integer" } });
+        node.Properties.Add(new SchemaProperty { Name = "label", Required = false, Schema = new SchemaNode { Type = "string" } });
+
+        var json = SchemaBuilderModel.Serialize(node);
+        Assert.Equal(
+            """{"type":"object","properties":{"id":{"type":"integer"},"label":{"type":"string"}},"required":["id"]}""",
+            json);
+    }
+
+    [Fact]
+    public void Serialize_Array_IncludesItems()
+    {
+        var node = new SchemaNode { Type = "array", Items = new SchemaNode { Type = "string" } };
+        Assert.Equal("""{"type":"array","items":{"type":"string"}}""", SchemaBuilderModel.Serialize(node));
+    }
+
+    [Fact]
+    public void Serialize_PropertiesWithBlankName_Skipped()
+    {
+        var node = new SchemaNode { Type = "object" };
+        node.Properties.Add(new SchemaProperty { Name = "", Schema = new SchemaNode { Type = "integer" } });
+        node.Properties.Add(new SchemaProperty { Name = "valid", Schema = new SchemaNode { Type = "string" } });
+
+        var json = SchemaBuilderModel.Serialize(node);
+        Assert.Equal("""{"type":"object","properties":{"valid":{"type":"string"}},"required":["valid"]}""", json);
+    }
+
+    // ── Round-trip ────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void RoundTrip_Parse_Then_Serialize_Stable()
+    {
+        const string original = """{"type":"object","properties":{"id":{"type":"integer"},"tags":{"type":"array","items":{"type":"string"}}},"required":["id"]}""";
+        var node = SchemaBuilderModel.Parse(original, SchemaBuilderModel.NewObject());
+        var roundTripped = SchemaBuilderModel.Serialize(node);
+        Assert.Equal(original, roundTripped);
+    }
+}