port the make list functions and JWT, and expose the framework variables to hooks

lib/str.sh gains firstword, lastword, or, patsubst, filter, filter_out,
addprefix, addsuffix and jwt: what the catalogue .mk files are written in.
The make JWT macro split on the commas of its payload; this one does not.

lib/context.sh registers COMPOSE_PROJECT_NAME, APP, DOCKER_NETWORK_* and the
rest as lazy defaults, so a converted .mk keeps reading them as it did.

Hooks also load a directory-level _stack.env and _stack.sh, for the .mk files
of the catalogue that hold settings for several stacks at once.

lib/context.sh

@@ -0,0 +1,63 @@
+#shellcheck shell=sh
+# shellcheck disable=SC3028  # HOSTNAME is a myos variable, set by bin/myos
+# context: what the requested stacks resolve to, and the framework variables a
+# stack hook may read.
+#
+# A hook is written the way a .mk was: it may mention COMPOSE_PROJECT_NAME,
+# USER or DOMAIN and expect the framework value. Those are registered as lazy
+# defaults, so each is computed when read and an explicit value still wins.
+
+# myos_all_compose_files  every compose file of every requested stack, in order
+myos_all_compose_files() {
+  for _ref in $MYOS_STACKS; do
+    myos_stack_compose_files "$_ref" 2>/dev/null
+  done
+  myos_framework_compose_files
+  return 0
+}
+
+# myos_first_app / myos_first_scope / myos_first_project
+# describe the first requested stack, which is what the introspection commands
+# report when several stacks are asked for at once.
+myos_first_app() {
+  for _ref in $MYOS_STACKS; do
+    case $_ref in
+      .|./*|/*|../*) basename "$(myos_stack_resolve "$_ref" 2>/dev/null)" ;;
+      *) myos_stack_name "$_ref" ;;
+    esac
+    return 0
+  done
+}
+
+myos_first_scope() {
+  for _ref in $MYOS_STACKS; do myos_scope "$_ref"; return 0; done
+}
+
+myos_first_project() {
+  for _ref in $MYOS_STACKS; do
+    myos_project_name "$(myos_scope "$_ref")" "$USER" "$ENV" "$(myos_first_app)"
+    return 0
+  done
+}
+
+# myos_context_defaults  register the framework variables as lazy defaults
+# shellcheck disable=SC2329  # these are reached through myos_var
+myos_context_defaults() {
+  myos_default_APP()                       { myos_first_app; }
+  myos_default_APP_NAME()                  { myos_name "$(myos_first_app)"; }
+  myos_default_SCOPE()                     { myos_first_scope; }
+  myos_default_COMPOSE_PROJECT_NAME()      { myos_first_project; }
+  myos_default_COMPOSE_SERVICE_NAME()      { myos_service_name "$(myos_first_project)"; }
+  myos_default_DOCKER_REPOSITORY()         { printf '%s' "$(myos_first_project)" | tr '_-' '//'; }
+  myos_default_DOCKER_NETWORK_DEFAULT()    { myos_network_default "$(myos_first_project)"; }
+  myos_default_DOCKER_NETWORK_PRIVATE()    { myos_network_private "$USER" "$ENV"; }
+  myos_default_DOCKER_NETWORK_PUBLIC()     { myos_network_public "${HOSTNAME:-}"; }
+  myos_default_DOCKER_NETWORK()            { myos_network_private "$USER" "$ENV"; }
+  myos_default_DOCKER_IMAGE_TAG()          { printf 'latest'; }
+  myos_default_GIT_USER()                  { printf '%s' "$USER"; }
+  myos_default_HOST_COMPOSE_PROJECT_NAME() { printf '%s' "${HOSTNAME:-}"; }
+  myos_default_HOST_DOCKER_VOLUME()        { printf '%s' "${HOSTNAME:-}"; }
+  myos_default_HOST_DOCKER_REPOSITORY()    { printf '%s' "${HOSTNAME:-}" | tr '_-' '//'; }
+  myos_default_USER_COMPOSE_PROJECT_NAME() { myos_resu "${MAIL:-}" | tr '.' '-'; }
+  myos_default_RESU()                      { myos_resu "${MAIL:-}"; }
+}