deps: the pins advance, and this repository gets a committed gate

libavr moves to its USI I2C rate accounting, the two override surfaces the
fan-controller port filed - a PWM solve that can be pinned, a capture edge that
is a value - and the shared preset loop's own fix. pureboot moves with it. This
firmware names none of them and no image moved.

`tools/check.sh` is new, and its absence was the defect: there was no committed
gate at all, so "run the suite" was a snippet somebody remembered - and the
order in a snippet is the one thing nobody re-derives. Every preset built
before any is tested is subtle and load-bearing, because the mode-identity
check reads the sibling mode's tree and a build-then-test-per-preset run holds
a fresh image against a stale sibling. The loop is libavr's
`tools/check-presets.sh`.

Two defaults stop being the editing machine's. `.vscode/settings.json` named
`D:/dev/libavr/local/toolchain/avr-gcc-16.1.0-mingw`, which is a path true of
one machine (libavr guidance rule 50) and, since the in-repo toolchain copies
went, true of none - `local/machine.cmake` is where a checkout says that and it
already did. And `.gitattributes` gains `* text=auto eol=lf`: naming the source
extensions left Markdown, Python, shell and CMake to whatever wrote them, which
on the Windows side is CRLF, and a rewrite there buries the change it made.

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

tools/check.sh

@@ -0,0 +1,11 @@
+#!/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
+# 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.
+set -euo pipefail
+cd "$(dirname "${BASH_SOURCE[0]}")/.."
+"${LIBAVR_ROOT:-libavr}/tools/check-presets.sh" "$@"