docs: comments state what is, not how it came to be

The loader build, the gate script and the line-ending rule each carried the
story of their arrival - a measurement off the bench, a loop got wrong by
hand, a checkout reached from two hosts - where a sentence of what holds now
is enough. .gitattributes loses two patterns for files this repository does
not have, .clangd its two non-ASCII dashes, two headers a "per C" that read
as a stripped degree sign, and the README a "(new)" and the port's own
first attempt at stopping monitor.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/check.sh

@@ -1,11 +1,10 @@
 #!/usr/bin/env bash
 # The task gate: every configure preset built, and only then every one tested.
 #
-# The loop itself is libavr's (tools/check-presets.sh) because the order in it
-# is subtle and was got wrong by hand more than once - the mode-identity checks
-# read the sibling mode's tree, so a build-then-test-per-preset run compares a
+# The loop is libavr's (tools/check-presets.sh): the mode-identity checks read
+# the sibling mode's tree, so a build-then-test-per-preset run would compare a
 # fresh image against a stale sibling. Anything this repository needs beyond
-# the presets is written after the call, where every tree is built and tested.
+# the presets goes after the call, where every tree is built and tested.
 set -euo pipefail
 cd "$(dirname "${BASH_SOURCE[0]}")/.."
 "${LIBAVR_ROOT:-libavr}/tools/check-presets.sh" "$@"