Add SessionStop hook and session-events.tsv duration tracking

- session-audit.json: add SessionStop entry pointing to new end-of-session scripts
- report-hook-event-end.sh/.ps1: log payload to hook-events.log and write TSV row to session-events.tsv
- report-hook-event.sh/.ps1: also write SessionStart TSV row to session-events.tsv so start/end pairs are queryable for duration

resources/scripts/report-hook-event.sh

@@ -10,6 +10,9 @@ mkdir -p -- "$state_dir"
 event_payload="$(cat)"
 printf '%s\n' "$event_payload" >> "$state_dir/hook-events.log"
 
+# Append a TSV row to session-events.tsv for duration tracking.
+printf '%s\tSessionStart\n' "$(date -u +"%Y-%m-%dT%H:%M:%SZ")" >> "$state_dir/session-events.tsv"
+
 if command -v node >/dev/null 2>&1 && [[ -f "$port_registry_script" ]]; then
 	if ! printf '%s' "$event_payload" | node "$port_registry_script"; then
 		printf '%s update-port-registry failed\n' "$(date -u +"%Y-%m-%dT%H:%M:%SZ")" >> "$state_dir/project-ports-errors.log"