Fix macOS compatibility: Add portable timeout helper

- Add utils.sh with cross-platform timeout functions for macOS compatibility
- Fix sf-logs-tail to use portable_timeout instead of GNU timeout command
- Fix test-all-wrappers.sh to use portable_timeout_seconds for testing
- Update README.md with macOS compatibility documentation

The timeout command is not available by default on macOS, causing
sf-logs-tail and test scripts to fail. The new utils.sh provides
fallback timeout functionality that works on Linux, macOS with/without
GNU coreutils, maintaining exit code 124 compatibility.

sf-logs-tail

@@ -3,6 +3,9 @@
 # Debug logs tail wrapper for Salesforce CLI
 # Provides real-time debug log monitoring with filtering and formatting
 
+# Source utilities for cross-platform compatibility
+source "$(dirname "$0")/utils.sh"
+
 # Color codes for output formatting
 readonly RED='\033[0;31m'
 readonly GREEN='\033[0;32m'
@@ -291,7 +294,7 @@ if [[ "$VERBOSE" == true ]]; then
 fi
 
 # Start the log tailing with timeout
-timeout "${DURATION}m" sf "${SF_ARGS[@]}" 2>/dev/null | while IFS= read -r line; do
+portable_timeout "$DURATION" sf "${SF_ARGS[@]}" 2>/dev/null | while IFS= read -r line; do
     if should_show_log_entry "$line" "$FILTER_PATTERN" "$APEX_ONLY"; then
         format_log_entry "$line" "$SHOW_COLORS" "$VERBOSE"
     fi