build(Makefile): capture pre-commit output to log files (#22978)

pre-commit was noisy: every sub-target dumped full stdout/stderr to the
terminal, burying failures in pages of compiler output and lint details.

Teach timed-shell.sh a quiet mode via MAKE_LOGDIR: when set, recipe
output is redirected to per-target log files and a one-line status is
printed instead. When unset, behavior is unchanged (with a refreshed
output format).

Makefile changes:

- pre-commit creates a tmpdir, passes MAKE_LOGDIR to sub-makes
- Drop --output-sync=target (log files eliminate interleaving)
- Add --no-print-directory to suppress Entering/Leaving noise
- Split check-unstaged and check-untracked into separate defines
- Restyle both with colored indicators and clearer instructions
- Clean up tmpdir on success, preserve on failure for debugging

scripts/lib/timed-shell.sh

@@ -8,6 +8,9 @@
 #   SHELL := $(CURDIR)/scripts/lib/timed-shell.sh
 #   .SHELLFLAGS = $@ -ceu
 #
+# When MAKE_LOGDIR is set, recipe output is captured to a log file.
+# Otherwise output goes to stdout/stderr as normal.
+#
 # $(shell ...) uses SHELL but passes -c directly, not .SHELLFLAGS.
 # Detect this and delegate to bash without timing output.
 if [[ $1 == -* ]]; then
@@ -19,23 +22,32 @@ set -eu
 target=$1
 shift
 
-bold=$(tput bold 2>/dev/null) || true
+dim=$(tput dim 2>/dev/null) || dim=$(tput setaf 8 2>/dev/null) || true
 green=$(tput setaf 2 2>/dev/null) || true
 red=$(tput setaf 1 2>/dev/null) || true
 reset=$(tput sgr0 2>/dev/null) || true
 
 start=$(date +%s)
-echo "${bold}==> ${target}${reset}"
 
 set +e
-bash "$@"
+if [[ -n ${MAKE_LOGDIR:-} ]]; then
+	logfile="${MAKE_LOGDIR}/${target//\//-}.log"
+	bash "$@" >"$logfile" 2>&1
+else
+	printf '%s○%s %s\n' "$dim" "$reset" "$target"
+	bash "$@"
+fi
 rc=$?
 set -e
 
 elapsed=$(($(date +%s) - start))
 if ((rc == 0)); then
-	echo "${bold}${green}==> ${target} completed in ${elapsed}s${reset}"
+	printf '%s✓%s %s (%ds)\n' "$green" "$reset" "$target" "$elapsed"
 else
-	echo "${bold}${red}==> ${target} FAILED after ${elapsed}s${reset}" >&2
-	exit $rc
+	if [[ -n ${MAKE_LOGDIR:-} ]]; then
+		printf '%s✗%s %s (%ds) → %s\n' "$red" "$reset" "$target" "$elapsed" "$logfile"
+	else
+		printf '%s✗%s %s (%ds)\n' "$red" "$reset" "$target" "$elapsed"
+	fi
+	exit "$rc"
 fi