Add Valkey and PostgreSQL (closes #9)

Install valkey-server, valkey-tools and postgresql from apt. Ubuntu
26.04 ships Valkey 9 and PostgreSQL 18, replacing the postgresql16 the
audit pinned.

Model: deepseek-v4-pro

README.md

@@ -43,6 +43,8 @@ Image: `git.eeqj.de/sneak/baseimage`, built for `linux/amd64` and
 | Ghostscript     | apt                            | `gs`                           |
 | Ruby            | apt `ruby`, `ruby-dev`         | `/usr/bin/ruby`                |
 | Bundler         | apt `bundler`                  | `bundle` on `PATH`             |
+| Valkey          | apt `valkey-server`, `valkey-tools` | `valkey-server`, `valkey-cli` |
+| PostgreSQL      | apt `postgresql`               | `psql`, `postgres` under `/usr/lib/postgresql/*/bin` |
 
 Plus the usual odds and ends: `git`, `curl`, `wget`, `jq`, `rsync`,
 `openssh-client`, `zip`/`unzip`, `xz-utils`, `bzip2`, and the `-dev`

bin/test

@@ -32,6 +32,9 @@ vips -l | grep -i heif > /dev/null
     gs --version
     ruby --version
     bundle --version
+    valkey-server --version
+    valkey-cli --version
+    psql --version
 '
 
 echo "== $img: runit service lifecycle"

build.sh

@@ -31,7 +31,8 @@ apt-get -y install --no-install-recommends \
     zstd sqlite3 \
     libvips-dev libvips-tools libheif-dev libheif-plugin-aomenc \
     imagemagick ghostscript \
-    ruby ruby-dev bundler
+    ruby ruby-dev bundler \
+    valkey-server valkey-tools postgresql
 
 # --- Go (latest) -------------------------------------------------------------
 gover="$(curl -fsSL 'https://go.dev/VERSION?m=text' | head -n1)"
@@ -118,6 +119,9 @@ magick --version
 gs --version
 ruby --version
 bundle --version
+valkey-server --version
+valkey-cli --version
+psql --version
 hugo version
 node --version
 npm --version