chore: enforce LF line endings (gitattributes) for portable shell/python

.gitattributes

@@ -0,0 +1,11 @@
+# Normalise to LF everywhere so shell/python deployed on Linux keep working.
+* text=auto eol=lf
+*.sh  text eol=lf
+*.py  text eol=lf
+*.php text eol=lf
+*.js  text eol=lf
+*.css text eol=lf
+*.json text eol=lf
+*.md  text eol=lf
+*.yaml text eol=lf
+*.yml text eol=lf