test: the format and ASCII rules stop being a habit here too

libavr's guidance binds this repo, and its gate checked every chip's codegen
without ever checking whether the sources it compiled were clang-format clean
or ASCII. `libavr_format_test()` does both now, over this tree alone - the
oracle's assembly needs no exclusion, being in neither glob, which is the right
answer for a vendored reference whose text is the artifact.

The sizes this repo prints were already gated: `sizes.py check-readme` is the
shape the rest of the fleet has now copied.

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

CMakeLists.txt

@@ -16,10 +16,18 @@ if(NOT EXISTS ${LIBAVR_ROOT}/CMakeLists.txt)
 endif()
 add_subdirectory(${LIBAVR_ROOT} libavr-build)
 
+include(${LIBAVR_ROOT}/cmake/checks.cmake)
+
 if(PROJECT_IS_TOP_LEVEL)
 	add_compile_options(-Werror) # warnings are errors for the port's own code
 	enable_testing()
 
+	# Rules 11 and 33 over this repo's own sources. The oracle's assembly needs
+	# no exclusion: it is neither formatted nor ASCII-checked, being in neither
+	# glob, which is the right answer for a vendored reference whose text is
+	# the artifact.
+	libavr_format_test()
+
 	# The behavioral tests drive the real wire protocols over a simavr pty
 	# (as the host tools do) and actually flash the device. The runners are
 	# host programs built at configure time against libsimavr (C++23 - what