deps: the pin advances again, and the line ending stops being the editing machine's

The libavr pin moves to the preset loop's own fix. `tools/check-presets.sh` -
which this repository's gate calls - parsed `cmake --list-presets` by anchoring
a preset name's closing quote to the end of the line, and a preset carrying a
`displayName` is listed as `"name" - description`. The presets here are
undescribed, so the loop found them either way; one `displayName` away it would
have found none and said the repository had no presets. The loop has a test
aimed at it now, which it did not before - libavr runs none of its own presets
through it.

`.gitattributes` gains `* text=auto eol=lf`. Naming the source extensions left
Markdown, Python, shell and CMake to whatever wrote them, and on the Windows
side of this bench that is CRLF - which turns an eighty-line edit into a rewrite
of every file it touched and buries the change in the diff. Rule 50 carries the
sentence now, so it is the repository's default rather than a habit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.gitattributes

@@ -1,8 +1,11 @@
-*.h         eol=lf
-*.hpp       eol=lf
-*.c         eol=lf
-*.cpp       eol=lf
-.git*       eol=lf
+# Line endings are the repository's, not the editing machine's: this checkout
+# is reached from two hosts, and a file rewritten by a Windows tool comes back
+# with every line changed unless something says otherwise. Naming the source
+# extensions left Markdown, Python, shell and CMake to whatever the writing
+# tool defaulted to, which is CRLF on one of the two.
+* text=auto eol=lf
+
+# Atmel Studio writes these and expects them back.
 *.vcxproj*  eol=crlf
 *.cppproj   eol=crlf
 *.sln       eol=crlf