Add local Debian package + plain binary build task

Adds packaging/local-build.sh and packaging/extract-binaries.sh, reused by a
new VS Code task, to populate gitignored dist/ and bin/ directories with the
same build.sh/test.sh/run.sh scripts the Gitea and GitHub workflows run.

packaging/extract-binaries.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+# Extracts plain executables and shared libraries from built .deb artifacts.
+set -euo pipefail
+src=$(realpath "${1:?artifact directory required}")
+out=$(realpath "${2:?output binary directory required}")
+extract=$(mktemp -d)
+trap 'rm -rf "$extract"' EXIT
+shopt -s nullglob
+debs=("$src"/*.deb)
+[[ ${#debs[@]} -gt 0 ]] || { echo 'No .deb files found to extract' >&2; exit 1; }
+for deb in "${debs[@]}"; do
+    dpkg-deb -x "$deb" "$extract"
+done
+mkdir -p "$out"
+for dir in "$extract/usr/bin" "$extract/usr/sbin"; do
+    [[ -d $dir ]] || continue
+    find "$dir" -mindepth 1 -maxdepth 1 -type f -exec cp {} "$out/" \;
+done
+[[ -d $extract/usr/lib ]] && find "$extract/usr/lib" -mindepth 2 -maxdepth 2 -type f -name '*.so*' -exec cp {} "$out/" \;
+true