Fix Github Repository Push Issue

[dcloud347]

This pull request updates the context refinement prompt and output handling in ContextRefineNode, and fixes the GitHub token format for repository cloning. The main changes focus on improving prompt clarity, output format consistency, and authentication security.

Prompt and Output Format Improvements:

• The context refinement prompt now instructs users to provide their analysis in a structured format matching the ContextRefineStructuredOutput model, with a clear example in JSON format for guidance. This replaces the previous Python class-based output format and enhances clarity for downstream processing.
• The codebase structure is now referenced as "This is the codebase structure:" for better readability and is included in the prompt more consistently.

Code Handling Enhancements:

• The file tree is now stored as an instance variable (self.file_tree) in ContextRefineNode, and injected directly into prompts, simplifying prompt construction and avoiding double-brace escaping. [1] [2]

Security and Authentication Fix:

• The GitHub access token is now inserted in the HTTPS URL as x-access-token:{github_access_token} instead of just {github_access_token}, following GitHub’s recommended authentication format for cloning repositories.