feat: grouped query builder with $upIf/$downIf condition groups

apps/monitor/src/query.rs

@@ -50,6 +50,17 @@ pub struct Response {
 pub fn evaluate(query: &Value, response: &Response) -> Result<bool> {
     match query {
         Value::Object(map) => {
+            // $upIf / $downIf — named groups, $downIf takes precedence
+            if map.contains_key("$upIf") || map.contains_key("$downIf") {
+                if let Some(down) = map.get("$downIf") {
+                    if evaluate(down, response).unwrap_or(false) { return Ok(false); }
+                }
+                if let Some(up) = map.get("$upIf") {
+                    return evaluate(up, response);
+                }
+                return Ok(true); // only $downIf set and didn't match → up
+            }
+
             // $and / $or / $not
             if let Some(and) = map.get("$and") {
                 let Value::Array(clauses) = and else { bail!("$and expects array") };