add two image convert functions

modules/media-process.nix

@@ -8,6 +8,7 @@
     flac
     unzip
     p7zip
+    imagemagick
   ];
 
   programs.zsh.initContent = ''
@@ -54,6 +55,24 @@
       shnsplit -f "$cue" -t "%n - %t" -o "$fmt" -d ./tracks "$audio"
     }
 
+    function image2webp() {
+      local dir="''${1:-.}"
+      find "$dir" -type f \( -iname '*.png' -o -iname '*.jpg' -o -iname '*.jpeg' \) | while read -r img; do
+        outfile="''${img%.*}.webp"
+        ${pkgs.imagemagick}/bin/magick "$img" -resize '1800>' -quality 82 "$outfile"
+        echo "Converted: $img -> $outfile"
+      done
+    }
+
+    function webp2png() {
+      local dir="''${1:-.}"
+      find "$dir" -type f -iname '*.webp' | while read -r img; do
+        outfile="''${img%.*}.png"
+        ${pkgs.imagemagick}/bin/magick "$img" "$outfile"
+        echo "Converted: $img -> $outfile"
+      done
+    }
+
     function camera-copy() {
       local delete_source=0
       if [[ "$1" == "-d" || "$1" == "--delete" ]]; then