PocketFlow: Path Traversal in pocketflow-coding-agent Cookbook Example File Tools

The pocketflow-coding-agent cookbook example in The-Pocket/PocketFlow implements a `_path(workdir, p)` helper as a thin os.path.join(workdir, p) wrapper with no canonicalization or containment check, used unguarded by the ReadFile, ListFiles, PatchRead, and PatchApply file-access tools. Because os.path.join returns an absolute `p` unchanged (ignoring workdir) and does not resolve '../' sequences, an agent invocation whose file-tool arguments include an absolute path or a traversal sequence can read or write files outside the configured working directory. Severity reflects that this affects an illustrative cookbook example rather than a core library API; applications that copy this pattern into production are affected.