fix: make prime_profile.sh fail loudly instead of exiting 0 or dying silently

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/prime_profile.sh

@@ -35,11 +35,12 @@ RECIPIENTS=()
 # shellcheck source-path=SCRIPTDIR source=scripts/lib_signal.sh
 . "${SCRIPT_DIR}/lib_signal.sh"
 
+# Prints only. The caller decides the exit code, so a usage *error* cannot
+# exit 0 and be read as success by whatever ran this.
 usage() {
 	echo "Usage: ${SCRIPT_NAME} +<E164 number> [+<E164 number> ...]"
 	echo "Sends one DM from the bot so the recipient's client learns its"
 	echo "profile key, which makes a later group add land as a real join."
-	exit 0
 }
 
 validate_requirements() {
@@ -47,7 +48,8 @@ validate_requirements() {
 	command -v jq >/dev/null || { echo "Error: jq is required" >&2; exit 1; }
 	if [[ ${#RECIPIENTS[@]} -eq 0 ]]; then
 		echo "Error: at least one recipient number is required" >&2
-		usage
+		usage >&2
+		exit 1
 	fi
 	local number
 	for number in "${RECIPIENTS[@]}"; do
@@ -66,7 +68,11 @@ validate_requirements() {
 # typed twice is a number that can be typed differently the second time.
 bot_number() {
 	local number
-	number="$(grep -E '^PHONE_NUMBER=' "${REPO_ROOT}/.env" | head -1 | cut -d= -f2-)"
+	# `|| true`: under `set -e` a grep that matches nothing kills the whole
+	# subshell, so the error message below would never print and the script
+	# would exit 1 silently -- the failure mode this repo exists to gate.
+	number="$(grep -E '^PHONE_NUMBER=' "${REPO_ROOT}/.env" || true)"
+	number="$(printf '%s' "$number" | head -1 | cut -d= -f2-)"
 	if [[ -z "$number" ]]; then
 		echo "Error: PHONE_NUMBER is not set in ${REPO_ROOT}/.env" >&2
 		return 1
@@ -113,6 +119,7 @@ while [[ $# -gt 0 ]]; do
 	case $1 in
 		-h | --help)
 			usage
+			exit 0
 			;;
 		-*)
 			echo "Unknown option: $1" >&2