feat(resolvespec): add 'contains' operator for array overlap

* Implemented 'contains' operator using BuildArrayOverlapCondition for real array containment.
* Updated documentation to clarify differences between text-cast ILIKE and array overlap.

pkg/resolvespec/filter_test.go

@@ -57,6 +57,36 @@ func TestBuildFilterCondition(t *testing.T) {
 			expectedCondition: "CAST(email AS TEXT) LIKE ?",
 			expectedArgsCount: 1,
 		},
+		{
+			name: "CONTAINS operator with single value",
+			filter: common.FilterOption{
+				Column:   "tags",
+				Operator: "contains",
+				Value:    "urgent",
+			},
+			expectedCondition: "tags && ARRAY[?]",
+			expectedArgsCount: 1,
+		},
+		{
+			name: "CONTAINS operator with multiple values",
+			filter: common.FilterOption{
+				Column:   "tags",
+				Operator: "contains",
+				Value:    []string{"urgent", "billing"},
+			},
+			expectedCondition: "tags && ARRAY[?,?]",
+			expectedArgsCount: 2,
+		},
+		{
+			name: "CONTAINS operator with empty value",
+			filter: common.FilterOption{
+				Column:   "tags",
+				Operator: "contains",
+				Value:    nil,
+			},
+			expectedCondition: "",
+			expectedArgsCount: 0,
+		},
 	}
 
 	for _, tt := range tests {

pkg/resolvespec/handler.go

@@ -1895,6 +1895,11 @@ func (h *Handler) buildFilterCondition(filter common.FilterOption) (conditionStr
 		if condition == "" {
 			return "", nil
 		}
+	case "contains":
+		condition, args = common.BuildArrayOverlapCondition(filter.Column, filter.Value)
+		if condition == "" {
+			return "", nil
+		}
 	default:
 		return "", nil
 	}
@@ -1939,6 +1944,11 @@ func (h *Handler) applyFilter(query common.SelectQuery, filter common.FilterOpti
 		if condition == "" {
 			return query
 		}
+	case "contains":
+		condition, args = common.BuildArrayOverlapCondition(filter.Column, filter.Value)
+		if condition == "" {
+			return query
+		}
 	default:
 		return query
 	}