Show the build's progress during an install, and drop the centre-count note where it does not apply

hardware/common/kit.sh

@@ -288,6 +288,9 @@ center_note() {
     local steps="$1" ax="$2"
     [[ -z $steps ]] && return 0
     local half=$(( steps / 2 ))
+    # Only when it matters: the 500000 default is fine for any travel under a
+    # million counts, and a note demanding a change nobody needs gets acted on.
+    (( half >= 500000 )) || return 0
     echo "; NOTE: half this travel is $half counts, so config.ini needs"
     echo ";   [Motor] ${ax}_center_count = $(kit_center_for "$steps")    (or anything above $half)"
     echo ";   The 500000 default would put the negative end at $(( 500000 - half ))."

scripts/install-tower

@@ -865,10 +865,29 @@ if [[ ${DO[preconditions]} == change ]]; then hr preconditions; sudo "$KIT/insta
 if [[ ${DO[vimba]} == change ]]; then hr vimba; sudo "$KIT/install.sh" --vimba "$VIMBA_SRC"; done_step vimba; fi
 
 hr "host build"
+build_start=$SECONDS
+say "configuring (a first build also downloads the MQTT and dashboard libraries)"
 ( cd "$REPO" && GIT_REV="$S_SW_REV" cmake -S . -B build -DWITH_MQTT=ON \
       -DWITH_VIMBA=$([[ -d /opt/VimbaX/cti ]] && echo ON || echo OFF) > "$WORK/cmake.log" 2>&1 ) ||
     { tail -20 "$WORK/cmake.log" >&2; die "cmake configure failed"; }
-( cd "$REPO" && cmake --build build -j"$(nproc)" 2>&1 | tail -3 )
+# Progress, not silence: a first build on a LattePanda takes 10-25 minutes, and a
+# screen that says nothing for that long reads as a hang - someone pressed Ctrl-C
+# on staeffelsberg. A line every 5 %, any error as it happens; the whole output
+# is kept, and its tail shown if the build fails.
+say "building on $(nproc) cores - a first build takes 10-25 minutes, a rebuild a few"
+if ! ( cd "$REPO" && cmake --build build -j"$(nproc)" 2>&1 ) | tee "$WORK/build.log" | awk '
+        match($0, /^\[ *[0-9]+%\]/) {
+            p = substr($0, 2, RLENGTH - 3) + 0
+            if (p >= last + 5 || (p == 100 && last != 100)) {
+                printf "   %3d%%  %s\n", p, substr($0, RLENGTH + 2); last = p; fflush()
+            }
+            next
+        }
+        /[Ee]rror/ { print "   " $0; fflush() }'; then
+    tail -30 "$WORK/build.log" >&2
+    die "the build failed (the last lines are above)"
+fi
+say "built in $(( (SECONDS - build_start) / 60 )) min $(( (SECONDS - build_start) % 60 )) s"
 [[ -x $BIN && -x $FGC_CONFIG ]] || die "the build did not produce the program and fgc-config"
 done_step build