fix(marker): fix inheritance hook, topology load, update sync, and asdict

Bugs found via end-to-end testing of project-level marker definitions:

1. New links didn't inherit — apply_defs_to_new_link is async but was
   called without await in UDPLink.create().

2. Project load crashed — load_project passed marker_definitions to
   Project.__init__. Now popped in load_project and restored separately
   in Project.open() (it backs a read-only property).

3. PUT on a definition didn't sync to links — update_marker's guard
   rejected even the project-layer sync call. Added an `inherited`
   bypass flag used by update_marker_definition.

4. _ubridge_add_marker_filter raised re.PatternError — the name regex
   used (?i)(?!global) look-around, invalid in Python's re module.
   Dropped the prefix check there: "global-*" names are legitimate at
   the uBridge boundary (inherited definitions); forbidden only at the
   user-facing schema.

5. GET /links hid inherited markers — asdict()'s runtime branch used
   _persist_markers() (which filters inherited markers). Restored
   self._markers for the runtime branch; only the topology_dump branch
   filters (inherited markers are rebuilt from definitions on load).

6. Duplicate "already exists" warnings on project open — open() fanned
   out definitions to all links, but UDPLink.create() had already done
   so via its inheritance hook. Removed the redundant fan-out in open().

gns3server/controller/link.py

@@ -641,7 +641,7 @@ class Link:
             "capture_compute_id": self.capture_compute_id,
             "link_type": self._link_type,
             "filters": self._filters,
-            "markers": self._persist_markers(),
+            "markers": self._markers,
             "suspend": self._suspended,
             "link_style": self._link_style,
             "wireshark": self._wireshark,