feat(makefile): add module build targets and helper scripts

Split module image build into build-modules-sdk and
build-modules-images; build-modules
now depends on both. Factor container engine detection and version
parsing into
scripts/container-env.sh and scripts/pyproject-version.sh respectively.
Add Makefile
variables for SDK/module paths and image naming, update help output, and
simplify
clean target to remove common caches and .pyc files.

scripts/pyproject-version.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+# Extract the version from a pyproject.toml file.
+# Usage: pyproject-version.sh <path/to/pyproject.toml> [default]
+# Prints the version string, or the default (0.0.1) if not found.
+
+PYPROJECT="${1:?Usage: pyproject-version.sh <pyproject.toml> [default]}"
+DEFAULT="${2:-0.0.1}"
+
+version=$(grep -m1 '^version\s*=' "${PYPROJECT}" 2>/dev/null \
+    | sed 's/^version\s*=\s*//;s/"//g;s/\s*$//')
+
+echo "${version:-${DEFAULT}}"