Docs: Clarify contract output handling

bin/panama

@@ -89,8 +89,10 @@ ${BOLD}Commands:${RESET}
               pattern to run a subset. --safe selects hermetic contracts only.
               Plain terminal runs prompt before non-hermetic work. Automation
               must grant each required capability with a repeatable --allow.
-              Failures print captured stdout/stderr; the default outer timeout
-              is 180 seconds.
+              Failures print captured stdout/stderr. Successful stdout stays
+              quiet; successful stderr is a warning. The default outer timeout
+              is 180 seconds. Set PANAMA_TEST_TIMEOUT_SECONDS to a positive
+              integer to override it.
   ${GREEN}contracts${RESET}   Name the contracts that mention a given file, each labeled
               with manifest capabilities. A heuristic over the text of tests/, so it
               answers "what should I run" rather than "what covers this".
@@ -491,7 +493,9 @@ is_contract_capability() {
 # each external capability it skipped. A plain terminal run asks before any
 # selected non-hermetic work. Automation must grant every required capability
 # with repeatable --allow flags. Each contract gets an outer timeout, 180
-# seconds by default, and failures include the captured stdout and stderr.
+# seconds by default. PANAMA_TEST_TIMEOUT_SECONDS accepts a positive integer
+# override. Failures include captured stdout and stderr. Successful stdout stays
+# quiet, while successful stderr is surfaced as a warning.
 cmd_test() {
   local timeout_seconds="${PANAMA_TEST_TIMEOUT_SECONDS:-180}"
   [[ "$timeout_seconds" =~ ^[1-9][0-9]*$ ]] || {