Fix project rename and duplicate issues

Fixes #2759

When renaming a project:
- Update self._filename to match the new project name
- Rename the .gns3 file on disk to keep it in sync
- Add error handling for file rename failures

When duplicating a project:
- Use self._filename (actual filename) instead of self.name
- This handles the case where a project has been renamed
- Prevents 'No such file or directory' errors

The root cause was that project renaming only updated the project name
in memory and in the .gns3 file content, but did not update the actual
.gns3 filename. This caused duplicate operations to fail because they
tried to read a file with the new name that didn't exist.

gns3server/controller/project.py

@@ -428,7 +428,21 @@ class Project:
 
     @name.setter
     def name(self, val):
+        old_filename = self._filename
         self._name = val
+        self._filename = val + ".gns3"
+
+        # Rename the .gns3 file on disk when the project name changes
+        if old_filename != self._filename:
+            old_path = os.path.join(self._path, old_filename)
+            new_path = os.path.join(self._path, self._filename)
+            if os.path.exists(old_path):
+                try:
+                    shutil.move(old_path, new_path)
+                    log.info(f"Project file renamed from '{old_filename}' to '{self._filename}'")
+                except OSError as e:
+                    log.warning(f"Could not rename project file from '{old_filename}' to '{self._filename}': {e}")
+                    self._filename = old_filename
 
     @property
     def id(self):
@@ -1404,7 +1418,11 @@ class Project:
         # copy dir
         await wait_run_in_executor(shutil.copytree, self.path, new_project_path.as_posix(), symlinks=True, ignore_dangling_symlinks=True)
         log.info("Project content copied from '{}' to '{}' in {}s".format(self.path, new_project_path, time.time() - t0))
-        topology = json.loads(new_project_path.joinpath('{}.gns3'.format(self.name)).read_bytes())
+
+        # Read the topology file using the actual filename (self._filename), not self.name
+        # This handles the case where a project has been renamed but we need to read the actual file
+        old_gns3_file = new_project_path.joinpath(self._filename)
+        topology = json.loads(old_gns3_file.read_bytes())
         project_name = name or topology["name"]
         # If the project name is already used we generate a new one
         project_name = self.controller.get_free_project_name(project_name)
@@ -1428,7 +1446,8 @@ class Project:
         if os.path.isdir(snapshots_dir):
             await update_snapshots(snapshots_dir, new_project_path, project_name, new_project_id)
 
-        os.remove(new_project_path.joinpath('{}.gns3'.format(self.name)))
+        # Remove the old .gns3 file (which has the original project name)
+        os.remove(old_gns3_file)
         project = await self.controller.load_project(dot_gns3_path, load=False)
         log.info("Project '{}': fast duplicated in {:.4f} seconds".format(project.name, time.time() - t0))
         return project