Initial import of the public datacenter bingo site

The bingo card ran inside the asxpio container, dispatched by Host.
Give the public site its own repo, image and deploy so it can be
released and mirrored independently of asxp.io.

Editing stays in the asxp.io admin, which keeps owning the schema and
the photo pipeline; this app only reads the shared bingo tables and the
bingo/ photos, through a read-only DB role and MinIO user. Tests load a
snapshot of the asxpio-built schema (test/schema.sql).

Assisted-by: Claude:opus-5

flake.nix

@@ -0,0 +1,46 @@
+{
+  description = "Datacenter bingo (datacenterbingo.xyz)";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+    in
+    {
+      devShells.${system}.default = pkgs.mkShell {
+        buildInputs = [
+          pkgs.ruby_3_4
+          pkgs.bundler
+          pkgs.openssl
+          pkgs.zlib
+          pkgs.libyaml
+          pkgs.postgresql.lib
+          pkgs.postgresql
+        ];
+
+        shellHook = ''
+          export GEM_HOME="$PWD/.gems"
+          export PATH="$GEM_HOME/bin:$PATH"
+          export BUNDLE_PATH="$GEM_HOME"
+
+          if [ -f .env ]; then
+            set -a
+            source .env
+            set +a
+          fi
+
+          if [ ! -f .gems/.bundled ] || [ Gemfile -nt .gems/.bundled ]; then
+            echo "Installing gems..."
+            bundle install --quiet && mkdir -p .gems && touch .gems/.bundled
+          fi
+
+          echo "bingo dev shell ready"
+          echo "  bundle exec rerun -- rackup -p 3000   - start with auto-reload"
+        '';
+      };
+    };
+}