Function resolve_include_files 

pub fn resolve_include_files(
    config: &WorktreeInitConfig,
    source_root: &Path,
) -> CoreResult<Vec<PathBuf>>

Resolve all include patterns from config and the .worktree-include file, then expand them against source_root and return the set of matching relative paths (deduplicated, sorted).

Missing .worktree-include file is not an error — only config patterns are used. Empty patterns are silently ignored.