Root-cause fix for mixed CRLF/LF in the repo (no .gitattributes previously).
Adds '* text=auto eol=lf' and explicit binary rules so all future checkouts
are LF. Renormalizes all tracked text files (no logical content change).
Backup tags: image qihuaiflow:backup-lineend-20260725-121632, git backup-lineend-pre-20260725-121632.