add .gitattributes: force *.sh to LF

entrypoint.sh has a /bin/sh shebang; CRLF would break exec in the Linux
container. Keep shell scripts LF-only regardless of Windows autocrlf.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitattributes

@@ -0,0 +1,2 @@
+# shell-скрипты всегда с LF — CRLF ломает shebang/exec в Linux-контейнере
+*.sh text eol=lf