fix: add missing fail() function in setup-pty-sidecar.sh

- Added RED color constant
- Added fail() function definition
- Fixes 'fail: command not found' error during setup

scripts/setup-pty-sidecar.sh

@@ -7,10 +7,12 @@ set -euo pipefail
 
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
+RED='\033[0;31m'
 NC='\033[0m'
 
 ok()   { echo -e "  ${GREEN}✓${NC} $1"; }
 warn() { echo -e "  ${YELLOW}!${NC} $1"; }
+fail() { echo -e "  ${RED}✗${NC} $1"; }
 skip() { echo -e "  - $1 (already set up)"; }
 
 SERVICE_NAME="officer-pty-sidecar"