Fix CRLF corruption in fx.sh, add .gitattributes to prevent recurrence

The previous commit's fx.sh was silently checked out with CRLF line
endings because this clone's core.autocrlf was true -- git converted
LF to CRLF on checkout, and every subsequent edit/copy carried that
corruption forward. Undetected by `sh` on the dev host (tolerant of
CRLF), but busybox ash on the actual AdaptiveOS target is not: booting
the resulting apkovl produced real syntax errors and ": not found" on
every corrupted line, confirmed by testing the rebuilt ISO in QEMU.

Fix: stripped all CR bytes, set core.autocrlf=false locally, and added
.gitattributes (* text=auto eol=lf) so this can't recur for any future
clone regardless of the cloning user's global git config.

.gitattributes

@@ -0,0 +1 @@
+* text=auto eol=lf