Arbitrary PNG file write via unchecked output path

Path traversal in MCPyATS 0.1.0 through 0.1.4 allows local users to write PNG files to attacker-selected writable paths. The generate_mermaid_markdown tool passes caller-controlled folder and name values through processGenerateRequest to path.join and fs.writeFileSync without confining the result to an output directory. Low-privileged access to the local MCP client is required; the server account can create directories and overwrite predictable .png paths wherever it has write permission.