Discourse: build libvips 8.18 for its image worker (#18430)

Discourse enabled libvips image processing by default and its worker refuses anything older than 8.18; Debian 13 ships 8.16, so the service failed to boot after an update and on fresh installs. Build the latest libvips release from source like discourse_docker does, on install and on update when a new release is out.

ct/discourse.sh

@@ -58,6 +58,17 @@ function update_script() {
   $STD git pull origin main
   msg_ok "Updated Discourse"
 
+  if check_for_gh_release "libvips" "libvips/libvips"; then
+    ensure_dependencies meson ninja-build pkg-config libglib2.0-dev libexpat1-dev libjpeg-dev libpng-dev libwebp-dev libtiff-dev libheif-dev libjxl-dev librsvg2-dev libcgif-dev libexif-dev liblcms2-dev liborc-0.4-dev libimagequant-dev libpango1.0-dev
+    CLEAN_INSTALL=1 fetch_and_deploy_gh_release "libvips" "libvips/libvips" "prebuild" "latest" "/opt/libvips" "vips-*.tar.xz"
+    msg_info "Building libvips"
+    cd /opt/libvips
+    $STD meson setup build --prefix=/usr/local --libdir=lib --buildtype=release -Dmodules=disabled -Dmagick=disabled -Dexamples=false
+    $STD ninja -C build install
+    ldconfig
+    msg_ok "Built libvips"
+  fi
+
   msg_info "Updating Dependencies"
   RUBY_TARGET=$(grep -A1 '^RUBY VERSION' /opt/discourse/Gemfile.lock | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -n1)
   RUBY_VERSION="${RUBY_TARGET:-4.0.7}" RUBY_INSTALL_RAILS="false" setup_ruby

install/discourse-install.sh

@@ -25,9 +25,36 @@ $STD apt install -y \
   gsfonts \
   brotli \
   nginx \
-  redis-server
+  redis-server \
+  meson \
+  ninja-build \
+  pkg-config \
+  libglib2.0-dev \
+  libexpat1-dev \
+  libjpeg-dev \
+  libpng-dev \
+  libwebp-dev \
+  libtiff-dev \
+  libheif-dev \
+  libjxl-dev \
+  librsvg2-dev \
+  libcgif-dev \
+  libexif-dev \
+  liblcms2-dev \
+  liborc-0.4-dev \
+  libimagequant-dev \
+  libpango1.0-dev
 msg_ok "Installed Dependencies"
 
+fetch_and_deploy_gh_release "libvips" "libvips/libvips" "prebuild" "latest" "/opt/libvips" "vips-*.tar.xz"
+
+msg_info "Building libvips"
+cd /opt/libvips
+$STD meson setup build --prefix=/usr/local --libdir=lib --buildtype=release -Dmodules=disabled -Dmagick=disabled -Dexamples=false
+$STD ninja -C build install
+ldconfig
+msg_ok "Built libvips"
+
 msg_info "Cloning Discourse"
 $STD git clone --depth 1 https://github.com/discourse/discourse.git /opt/discourse
 msg_ok "Cloned Discourse"