ci: rename update-scripts → ci

This changes how we think about this directory; it does not need to be
exclusively for scripts related to updates, but should be a place for
any scripts intended to be run by CI workflows.

This mindset should make it easier to develop and test the business
logic of workflows, without always needing to test "in production" on
the nixvim repo or a fork.

update-scripts/update.nix

@@ -1,109 +0,0 @@
-{
-  nix,
-  writeShellApplication,
-}:
-writeShellApplication {
-  name = "update";
-
-  runtimeInputs = [
-    nix
-  ];
-
-  text = ''
-    commit=
-    use_github_output=
-    while [ $# -gt 0 ]; do
-      case "$1" in
-      --commit) commit=1
-        ;;
-      --github-output) use_github_output=1
-        ;;
-      --*) echo "unknown option $1"
-        ;;
-      *) echo "unexpected argument $1"
-        ;;
-      esac
-      shift
-    done
-
-    update_args=( )
-    if [ -n "$commit" ]; then
-      update_args+=( "--commit-lock-file" )
-    fi
-
-    currentCommit() {
-      git show --no-patch --format=%h
-    }
-
-    hasChanges() {
-      old="$1"
-      new="$2"
-      if [ -n "$commit" ]; then
-        [ "$old" != "$new" ]
-      elif git diff --quiet; then
-        return 1
-      else
-        return 0
-      fi
-    }
-
-    writeGitHubOutput() {
-      if [ -n "$use_github_output" ] && [ -n "$commit" ]; then
-        {
-          echo "$1<<EOF"
-          git show --no-patch --format=%b
-          echo "EOF"
-        } >> "$GITHUB_OUTPUT"
-      fi
-    }
-
-    versionInfo() {
-      extra_args=( )
-      if [ "$1" = "--amend" ]; then
-        extra_args+=(
-          "--amend"
-          "--no-edit"
-        )
-      fi
-
-      nix-build ./update-scripts -A version-info
-      ./result/bin/version-info
-
-      if [ -n "$commit" ]; then
-        git add version-info.toml
-        git commit "''${extra_args[@]}"
-      fi
-    }
-
-    # Initialise version-info.toml
-    if [ ! -f version-info.toml ]; then
-      echo "Creating version-info file"
-      versionInfo -m "version-info: init"
-    fi
-
-    # Update the root lockfile
-    old=$(currentCommit)
-    echo "Updating root lockfile"
-    nix flake update "''${update_args[@]}"
-    new=$(currentCommit)
-    if hasChanges "$old" "$new"; then
-      echo "Updating version-info"
-      versionInfo --amend
-      writeGitHubOutput root_lock_body
-    fi
-
-    # Update the dev lockfile
-    root_nixpkgs=$(nix eval --raw --file . 'inputs.nixpkgs.rev')
-    old=$(currentCommit)
-    echo "Updating dev lockfile"
-    nix flake update "''${update_args[@]}" \
-        --override-input 'dev-nixpkgs' "github:NixOS/nixpkgs/$root_nixpkgs" \
-        --flake './flake/dev'
-    new=$(currentCommit)
-    if hasChanges "$old" "$new"; then
-      echo "Updating version-info"
-      versionInfo --amend
-      writeGitHubOutput dev_lock_body
-    fi
-  '';
-}