fix: propagate 405 when suspending a node without suspend support

Suspending a single VPCS/IOU node returned a fake 204: the controller
route swallowed the compute 405 that the node types honestly raise, so
callers saw success while the node stayed started. Surface the 405
instead. The best-effort swallow on suspend_all is kept (and now covered
by a test) since mixed projects legitimately contain always-running node
types.

gns3server/api/routes/controller/nodes.py

@@ -372,14 +372,13 @@ async def suspend_node(node: Node = Depends(dep_node)) -> None:
     """
     Suspend a node.
 
+    Node types without suspend support return a 405 error instead of a
+    silent no-op, so the caller cannot mistake it for a suspended node.
+
     Required privilege: Node.PowerMgmt
     """
 
-    try:
-        await node.suspend()
-    except HTTPException as e:
-        if not e.status_code == status.HTTP_405_METHOD_NOT_ALLOWED:
-            raise
+    await node.suspend()
 
 
 @router.post(