fix(docker): enable dev-settings feature by default in local builds

Local image builds via mise run cluster / mise run docker:build:*
were missing the dev-settings feature flag, causing e2e tests to fail
with 'unknown setting key dummy_bool'. CI sets EXTRA_CARGO_FEATURES
explicitly but the local path did not.

Default EXTRA_CARGO_FEATURES to openshell-core/dev-settings so local
builds match CI. The variable can still be overridden by the caller.

Author: drew

tasks/scripts/docker-build-image.sh

@@ -159,8 +159,12 @@ else
   exit 1
 fi
 
+# Default to dev-settings so local builds include test-only settings
+# (dummy_bool, dummy_int) that e2e tests depend on, matching CI behaviour.
+EXTRA_CARGO_FEATURES="${EXTRA_CARGO_FEATURES:-openshell-core/dev-settings}"
+
 FEATURE_ARGS=()
-if [[ -n "${EXTRA_CARGO_FEATURES:-}" ]]; then
+if [[ -n "${EXTRA_CARGO_FEATURES}" ]]; then
   FEATURE_ARGS=(--build-arg "EXTRA_CARGO_FEATURES=${EXTRA_CARGO_FEATURES}")
 fi