Fetch libmonet in build.sh and document monet colours

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

scripts/build.sh

@@ -27,6 +27,8 @@ commit=${FCITX_COMMIT:-${known_commits[$version]:-}}
 [ -n "$commit" ] || die "no pinned commit for Fcitx5 $version. Look up the commit of its tag and pass it as FCITX_COMMIT=<sha>"
 # Commit of the yoga submodule pinned by Fcitx5 (third_party/yoga).
 yoga_commit=${YOGA_COMMIT:-042f5013152eb81c1552dec945b88f7b95ca350f}
+# libmonet (header-only) supplies the colours derived from the desktop accent.
+monet_commit=${MONET_COMMIT:-b97a55ac75ae82435628dc585cccadb45e4d2feb}
 
 # fetch_commit <url> <dir> <commit>, leaves <dir> checked out at exactly <commit>
 fetch_commit() {
@@ -48,6 +50,8 @@ echo ">> fetching Fcitx5 $version ($commit)"
 fetch_commit https://github.com/fcitx/fcitx5 "$srcdir" "$commit"
 echo ">> fetching yoga ($yoga_commit)"
 fetch_commit https://github.com/facebook/yoga "$srcdir/third_party/yoga" "$yoga_commit"
+echo ">> fetching libmonet ($monet_commit)"
+fetch_commit https://git.oeo.one/justme/libmonet.git "$work/libmonet" "$monet_commit"
 [ -z "${FETCH_ONLY:-}" ] || { echo ">> sources are in place"; exit 0; }
 
 echo ">> overlaying m3ui"
@@ -61,6 +65,7 @@ fi
 echo ">> configuring"
 cmake -S "$srcdir" -B "$work/cmake" -G Ninja \
     -DCMAKE_BUILD_TYPE=Release \
+    -DMONET_INCLUDE_DIR="$work/libmonet/include" \
     -DCMAKE_INSTALL_PREFIX="${PREFIX:-$HOME/.local/m3ui}" \
     -DENABLE_X11=On -DENABLE_WAYLAND=On \
     -DENABLE_TEST=Off -DENABLE_TESTING_ADDONS=Off -DENABLE_ENCHANT=Off \