enhance: Add comprehensive .gitignore for deb-mock project

- Add mock-specific build artifacts (chroot/, mock-*, mockroot/)
- Include package build files (*.deb, *.changes, *.buildinfo)
- Add development tools (.coverage, .pytest_cache, .tox)
- Include system files (.DS_Store, Thumbs.db, ._*)
- Add temporary and backup files (*.tmp, *.bak, *.backup)
- Include local configuration overrides (config.local.yaml, .env.local)
- Add test artifacts and documentation builds
- Comprehensive coverage for Python build system project

This ensures build artifacts, chroot environments, and development
tools are properly ignored in version control.

mock/run-tests.sh

@@ -0,0 +1,38 @@
+#! /bin/bash
+
+script=$(readlink -f "$0")
+testdir=$(dirname "$script")/tests
+sourcedir=$(readlink -f "$testdir/../py")
+
+: "${PYTHON=/usr/bin/python3}"
+
+if test -n "$PYTHONPATH"; then
+    PYTHONPATH=$PYTHONPATH:$sourcedir
+else
+    PYTHONPATH=$sourcedir
+fi
+export PYTHONPATH
+
+debug() { echo >&2 " * $*" ; }
+
+debug "sourcedir:  $sourcedir"
+debug "testdir:    $testdir"
+debug "PYTHON:     $PYTHON"
+debug "PYTHONPATH: $PYTHONPATH"
+
+args=()
+cov=true
+for arg; do
+    case $arg in
+    --no-cov) cov=false ;;
+    *) args+=( "$arg" ) ;;
+    esac
+done
+
+cov_args=()
+if $cov; then
+    cov_args=( --cov-report term-missing --cov "$sourcedir" )
+fi
+
+set -x
+"$PYTHON" -B -m pytest "${cov_args[@]}" "$testdir" "${args[@]}"