The normalizeGitHubCopilotResponsesTools filter required type="function",
which dropped Claude-format tools (no type field, uses input_schema).
Relax the filter to accept tools without a type field and map input_schema
to parameters so tools are correctly sent to the upstream API.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
GitHub Copilot API rejects model names with suffixes (e.g. claude-opus-4.6(medium)).
The OAuthModelAlias resolution correctly maps aliases like 'opus(medium)' to
'claude-opus-4.6(medium)' preserving the suffix, but the executor must strip the
suffix before sending to the upstream API since Copilot only accepts bare model names.
Update normalizeModel in github_copilot_executor to strip suffixes using
thinking.ParseSuffix, matching the pattern used by other executors.
Also add test coverage for:
- OAuthModelAliasChannel github-copilot and kiro channel resolution
- Suffix preservation in alias resolution for github-copilot
- normalizeModel suffix stripping in github_copilot_executor
