feat: fix secrets permissions, move ./packages to flake outputs

packages/dirmir.nix

@@ -0,0 +1,24 @@
+{writers}:
+writers.writeDashBin "dirmir" ''
+  SOURCE="$1"
+  TARGET="$2"
+
+  if [ ! -d "$SOURCE" ] || [ $# -ne 2 ]; then
+    echo >/dev/stderr "Usage: dirmir SOURCE TARGET"
+    exit 1
+  fi
+
+  if [ -e "$TARGET" ]; then
+    echo >/dev/stderr "$TARGET" already exists. Please use a different name.
+    exit 1
+  fi
+
+  find "$SOURCE" | while read -r entry; do
+    if [ -d "$entry" ]; then
+      mkdir -p "$TARGET/$entry"
+    else
+      # create a file with the same permissions as $entry
+      install -m "$(stat -c %a "$entry")" /dev/null "$TARGET/$entry"
+    fi
+  done
+''