feat: bearer auth for netbox 4.5 v2 api tokens

v2 tokens (nbt_<key>.<secret>) are sent as Authorization: Bearer, legacy
tokens keep the Token scheme; NetBox drops legacy token support in 4.7.

tests/test_inventory.py

@@ -16,6 +16,14 @@ def make_client() -> inv.NetBoxClient:
     return inv.NetBoxClient(NETBOX_URL, "token", verify_ssl=True, timeout=5)
 
 
+class TestAuthHeader:
+    def test_legacy_token_uses_token_scheme(self):
+        assert inv.auth_header("0123456789abcdef") == "Token 0123456789abcdef"
+
+    def test_v2_token_uses_bearer_scheme(self):
+        assert inv.auth_header("nbt_abc.def") == "Bearer nbt_abc.def"
+
+
 class TestStripPrefix:
     def test_strips_prefix_length(self):
         assert inv.strip_prefix("192.0.2.10/24") == "192.0.2.10"