build: add missing security/lint targets

ober

bf889bec65dd0903d8beb1c685c0dfd3d6529516

diff --git a/Makefile b/Makefile
index 9eee4c8..2e9a669 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: all build test lint
+.PHONY: all build test lint security
 
 all:
 	@echo "jerboa-compat — Gerbil compatibility modules"
@@ -7,6 +7,14 @@ all:
 
 lint: build
 
+security:
+	@echo "==> security: high-confidence secret scan"
+	@if git grep -nIE '(AKIA[0-9A-Z]{16}|-----BEGIN (RSA |EC |OPENSSH )?PRIVATE KEY-----|aws_secret_access_key|GH_TOKEN|sk-[A-Za-z0-9]{20,})' -- ':!vendor' ':!*.lock' ':!test*' ':!Makefile' 2>/dev/null; then \
+		echo "SECURITY: potential secret detected" >&2; exit 1; \
+	else \
+		echo "security: no high-confidence secrets found"; \
+	fi
+
 build:
 	gxi build.ss