Check and fix common markdown formatting issues after writing or editing any .md file. MUST be invoked whenever you have just written or edited a markdown file (via Write or Edit tools). Checks table formatting, code-block fences, blank lines, ambiguous headers, and other rendering hazards; fixes what it can and flags what needs judgment. Also invoke on "check markdown", "fix formatting", "markdown格式", "表格格式", or a .md rendering wrong.
