fix: use bound-method param count for Dynamips create_nio detection

The inspect check tested unbound function signatures (3 params unbound vs
2 unbound) but node.manager.create_nio is a bound method — inspect
excludes 'self'.  Dynamips bound = 2 (node + nio_settings), standard
bound = 1 (nio_settings).  The old '== 3' never matched, so the extra
'node' arg was never passed.  Switch to '>= 2' and rewrite the test to
exercise the actual bound-method scenario.

gns3server/api/routes/compute/projects.py

@@ -191,8 +191,12 @@ async def create_batch_nios(
         nio_settings = jsonable_encoder(entry.nio, exclude_unset=True)
         # Dynamips.create_nio takes an extra positional `node` argument that
         # the base signature does not include. Detect it via parameter count.
+        # Dynamips.create_nio(self, node, nio_settings) exposes one extra
+        # positional on the bound method compared to the standard signature
+        # (self, nio_settings).  Detect it: standard == 1 bound param,
+        # Dynamips == 2 bound params (node + nio_settings).
         sig = inspect.signature(node.manager.create_nio)
-        if len(sig.parameters) == 3:
+        if len(sig.parameters) >= 2:
             nio = node.manager.create_nio(node, nio_settings)
         else:
             nio = node.manager.create_nio(nio_settings)