Function detect_context_with_warnings 

pub fn detect_context_with_warnings(
    target: Option<&str>,
    repo_root: &Path,
    needs_branch: bool,
) -> (TemplateContext, Vec<TemplateWarning>)

Detect context from target path and git repository

Returns the context and any warnings (e.g., git branch detection failures). Only attempts git branch detection if the template uses {{branch}}.