refactor(providers): define typed usage contract

nanobot/providers/github_copilot_provider.py

@@ -174,7 +174,12 @@ def login_github_copilot(
 class GitHubCopilotProvider(OpenAICompatProvider):
     """Provider that exchanges a stored GitHub OAuth token for Copilot access tokens."""
 
-    def __init__(self, default_model: str = "github-copilot/gpt-4.1"):
+    def __init__(
+        self,
+        default_model: str = "github-copilot/gpt-4.1",
+        *,
+        provider_name: str = "github_copilot",
+    ):
         from nanobot.providers.registry import find_by_name
 
         self._copilot_access_token: str | None = None
@@ -190,6 +195,7 @@ class GitHubCopilotProvider(OpenAICompatProvider):
                 "User-Agent": USER_AGENT,
             },
             spec=find_by_name("github_copilot"),
+            provider_name=provider_name,
         )
 
     async def _get_copilot_access_token(self) -> str: