tb-scripts: add ,optipng and ,zipdir utility scripts

Add two new shell utility scripts to the custom script packages:

,optipng - Parallel PNG optimization wrapper
- Detects available CPU cores and runs optipng in parallel using xargs
- Accepts optional file arguments, defaults to all *.png in current dir
- Uses maximum compression level (-o7) for best results
- Added to tb-dev-scripts package with optipng as runtime dependency

,zipdir - Quick directory archiving helper
- Creates a zip archive of the current directory
- Names the archive after the directory and places it in parent folder
- Uses maximum compression (-9) with extra attributes excluded (-X)
- Added to tb-scripts package with zip as runtime dependency

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

pkgs/tb-dev-scripts/optipng

@@ -0,0 +1,13 @@
+#!/bin/sh -x
+
+PROCS=$(grep -c ^processor /proc/cpuinfo)
+
+if [ $# -eq 0 ]; then
+    (for f in *.png; do
+         echo "$f";
+     done) | xargs -P"$PROCS" -d'\n' -n1 optipng -o7
+else
+    (for f in "$@"; do
+         echo "$f";
+     done) | xargs -P"$PROCS" -d'\n' -n1 optipng -o7
+fi