chore: import upstream snapshot with attribution

providers/github-copilot/provider.toml

@@ -0,0 +1,11 @@
+name = "GitHub Copilot"
+# Reasoning HTTP format (accessed 2026-06-25): POST /chat/completions.
+# Supported controls and values come from authenticated GET /models metadata
+# and can change by account/model; GitHub's public model comparison does not
+# document this private request schema or static mappings.
+# https://api.githubcopilot.com/models
+# https://docs.github.com/en/copilot/reference/ai-models/model-comparison
+env = ["GITHUB_TOKEN"]
+npm = "@ai-sdk/openai-compatible"
+doc = "https://docs.github.com/en/copilot"
+api= "https://api.githubcopilot.com"