fix: normalize marker.match event tag to int to match the REST schema

The WS event carried the tag as str (verbatim from the MARK signal) when
present and as int when falling back to the registry, so one tag reached
consumers as two different values. Parse the signal's decimal (the exact
value we installed via 'mark <bpf> tag <id>') and keep the registered int
on malformed input; None only when neither side carries one.

gns3server/compute/marker/marker_listener.py

@@ -114,13 +114,24 @@ class MarkerListener(asyncio.DatagramProtocol):
         # signals that carry no `link=`.
         signal_link = link if link and link != "-" else None
 
+        # Normalize the tag to int so the event matches the REST schema
+        # (MarkerCreate.tag is Optional[int]): the signal merely echoes the
+        # decimal we installed via `mark <bpf> tag <id>`, so parsing cannot
+        # fail for well-formed signals; a malformed value keeps the registered
+        # int, and the tag is None only when neither side carries one.
+        event_tag = registered_tag
+        if tag and tag != "-":
+            try:
+                event_tag = int(tag)
+            except ValueError:
+                pass  # malformed signal tag: keep the registered value
+
         event = {
             "project_id": project_id,
             "node_id": node_id,
             "link_id": signal_link or link_id,
             "filter": filter_name,
-            # Prefer the value carried in the signal; fall back to the one we registered.
-            "tag": tag if tag and tag != "-" else registered_tag,
+            "tag": event_tag,
             "ts": ts,
             "len": int(length) if length and length.isdigit() else 0,
             # Travel direction relative to the capture node (node_id above);