Fix Makefile guard to handle env vars with special characters

The guard-% macro used shell indirect expansion which breaks when
the variable contains JSON (quotes, newlines). Use printenv instead
which just checks if the variable is set without expanding its value.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: eakmanrq <6326532+eakmanrq@users.noreply.github.com>

Author: eakmanrq

Makefile

@@ -166,7 +166,7 @@ web-test:
 	pytest -n auto -m "web"
 
 guard-%:
-	@ if [ "${${*}}" = "" ]; then \
+	@ if ! printenv ${*} > /dev/null 2>&1; then \
 		echo "Environment variable $* not set"; \
 		exit 1; \
 	fi