Restructure repo layout, wiring src/ and packaging for local and distro builds

- Add dev runner main.py that prefers local src/ over installed pkgmgr
- Move Arch/Debian/Fedora packaging files under packaging/* and update build scripts
- Adjust .gitignore/.dockerignore for new packaging paths and src/source/
- Improve config defaults discovery to support src/ layout and installed packages
- Update architecture diagram and add TODO overview for TAGS/MIRROR/SIGNING_KEY

https://chatgpt.com/share/693a76a0-e408-800f-9939-868524cbef4d

scripts/installation/arch/package.sh

@@ -3,10 +3,21 @@ set -euo pipefail
 
 echo "[arch/package] Building Arch package (makepkg --nodeps)..."
 
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "${SCRIPT_DIR}/../.." && pwd)"
+PKG_DIR="${PROJECT_ROOT}/packaging/arch"
+
+if [[ ! -f "${PKG_DIR}/PKGBUILD" ]]; then
+  echo "[arch/package] ERROR: PKGBUILD not found in ${PKG_DIR}"
+  exit 1
+fi
+
+cd "${PKG_DIR}"
+
 if id aur_builder >/dev/null 2>&1; then
   echo "[arch/package] Using 'aur_builder' user for makepkg..."
-  chown -R aur_builder:aur_builder "$(pwd)"
-  su aur_builder -c "cd '$(pwd)' && rm -f package-manager-*.pkg.tar.* && makepkg --noconfirm --clean --nodeps"
+  chown -R aur_builder:aur_builder "${PKG_DIR}"
+  su aur_builder -c "cd '${PKG_DIR}' && rm -f package-manager-*.pkg.tar.* && makepkg --noconfirm --clean --nodeps"
 else
   echo "[arch/package] WARNING: user 'aur_builder' not found, running makepkg as current user..."
   rm -f package-manager-*.pkg.tar.*