push oci image and x86_64-*-gnu build to bin cache

This will allow most Nix users to use the `default` package and without
having to build from source. And also allows any weirdos to get the OCI
image from the Nix binary cache if they want. No idea why that would be
desireable though lol

bin/nix-build-and-cache

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+# The first argument must be the desired installable
+INSTALLABLE="$1"
+
+# Build the installable and forward any other arguments too
+nix build "$@"
+
+if [ ! -z ${ATTIC_TOKEN+x} ]; then
+
+nix run --inputs-from . attic -- login \
+    conduit \
+        https://nix.computer.surgery/conduit \
+        "$ATTIC_TOKEN"
+
+    push_args=(
+        # Attic and its build dependencies
+        "$(nix path-info --inputs-from . attic)"
+        "$(nix path-info --inputs-from . attic --derivation)"
+
+        # The target installable and its build dependencies
+        "$(nix path-info "$INSTALLABLE" --derivation)"
+        "$(nix path-info "$INSTALLABLE")"
+    )
+
+    nix run --inputs-from . attic -- push conduit "${push_args[@]}"
+else
+    echo "\$ATTIC_TOKEN is unset, skipping uploading to the binary cache"
+fi