Add User-Agent header to GitHub API requests in self-update

[Copilot]

GitHub API requests require a User-Agent header to avoid rate limiting and request rejection. The self-update command was making requests without this header.

Changes

• Added User-Agent: journal-cli/{version} header to GitHub API requests:
  • Release metadata fetch from /repos/{owner}/{repo}/releases/latest
  • Binary asset download
• Imported internal/version package to dynamically include version string

Implementation

req, err := http.NewRequest("GET", "https://api.github.com/repos/"+repo+"/releases/latest", nil)
if err != nil {
    return fmt.Errorf("failed to create request: %w", err)
}
req.Header.Set("User-Agent", "journal-cli/"+version.GetVersion())

resp, err := http.DefaultClient.Do(req)

The version string resolves to "dev" for development builds or the actual semantic version for releases.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.