docs(12-02): create comprehensive troubleshooting guide

- Add quick diagnosis section with debug logging instructions
- Document authentication errors (bad credentials, resource not accessible, not found)
- Document connection issues (ECONNREFUSED, timeout, server startup)
- Document MCP client issues (Claude, Cursor, VS Code, Windows-specific)
- Document AI feature issues (provider not configured, rate limits, fallback)
- Document GitHub API issues (rate limits, GraphQL errors, project not found)
- Add debug mode instructions and bug reporting template

Author: kunwarVivek