Whitespace & Line Ending Inspector

In short When an entire file shows as modified in a diff and you only changed one line, the cause is almost always line endings — your editor saved LF where the file had CRLF, or the reverse, and every line now differs. This reports which endings a file uses, whether they are mixed, where trailing whitespace sits and whether indentation mixes tabs and spaces, then normalises all of it in one pass. The permanent fix for the diff problem is a `.gitattributes` file declaring `text=auto` rather than each person configuring their editor, because that puts the rule in the repository where it survives new contributors. Trailing whitespace matters less than people argue about but is not entirely cosmetic: it produces noise in diffs, it is significant inside Markdown where two trailing spaces force a line break, and it can break here-documents and YAML in ways that are painful to debug. Mixed indentation is the one that causes real bugs — Python treats a tab as a different indent level from spaces, YAML rejects tabs outright, and a file that looks correctly aligned in one editor can be structurally wrong in another because the two render tab stops differently.