scripts: Add ShellCheck lint target

Add a tracked runner that discovers Bash scripts under scripts/ and
checks them with external source resolution enabled. Expose it through
the top-level Makefile.

Run the same entry point from the patch lint workflow whenever a range
touches Bash lint inputs, and report its result explicitly.

Makefile

@@ -102,6 +102,7 @@ SCST_SOURCE_FILES = $(shell if [ -e scripts/list-source-files ]; then	\
 help:
 	@echo "		tags                  : make tags"
 	@echo "		cov-build             : make coverity build"
+	@echo "		shellcheck            : check Bash scripts"
 	@echo ""
 	@echo "		all                   : make all"
 	@echo "		clean                 : clean files"
@@ -194,6 +195,9 @@ cov-build:
 			exit $$?;					   \
 	done
 
+shellcheck:
+	scripts/run-shellcheck
+
 all clean extraclean install uninstall:
 	if [ $@ = extraclean ]; then rm -f TAGS tags cscope.out; fi
 	for d in $(SCST_DIR) $(ISCSI_DIR) $(QLA_DIR) $(SRP_DIR)	     \
@@ -513,7 +517,7 @@ multiple-release-archives:
 2debug:
 	cd $(SCST_DIR) && $(MAKE) $@
 
-.PHONY: help tags cov-build all clean extraclean install uninstall \
+.PHONY: help tags cov-build shellcheck all clean extraclean install uninstall \
 	scst scst_clean scst_extraclean scst_install scst_uninstall \
 	docs docs_clean docs_extraclean \
 	scstadm scstadm_clean scstadm_extraclean scstadm_install scstadm_uninstall \