Add raw client error annotation and annotate GetFileContents

[omgitsads]

Annotate raw client errors in the context, to allow us to filter tool call failures in our metrics based on the error type.

[Copilot]

Pull request overview

This PR adds support for annotating raw client errors in the context to enable error-type-based filtering in metrics. The implementation follows the existing patterns for GitHub API and GraphQL errors.

Key changes:

• Introduced GitHubRawAPIError type and associated error handling functions
• Added raw error tracking to GitHubCtxErrors context structure
• Updated GetFileContents to use the new raw error annotation instead of generic error handling

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
pkg/errors/error.go	Adds GitHubRawAPIError type, context tracking, and NewGitHubRawAPIErrorResponse function for annotating raw API errors
pkg/github/repositories.go	Updates error handling in GetFileContents to use the new raw API error annotation

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

The test should verify the Error() method output for consistency with the other error type tests. The API error test (line 41) and GraphQL error test (line 63) both verify the Error() method output, but this test doesn't. Add an assertion like: assert.Equal(t, "failed to fetch raw content: raw content not found", rawError.Error())