fix(framework): per-session ticket files unblock parallel sessions [#439]

The ticket gate required the single .crush/active-ticket file, so two
concurrent sessions overwrote each other's ticket mid-work. The gate now
accepts any non-empty .crush/active-ticket* file; each session keeps its
own (e.g. active-ticket-plant, active-ticket-core). Also prune .crush/
session scratch from both shellcheck scanners so one session's throwaway
probe scripts cannot block the other session's commits. Documented in
AGENTS.md Task Tracking.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

tests/shellcheck.sh

@@ -36,7 +36,8 @@ mapfile -t FILES < <(
         *) echo "$f_abs" ;;
       esac
     done < <(find "$ROOT" -type f -name '*.sh' \
-               -not -path '*/.git/*' -not -path "$ROOT/vendor/*")
+               -not -path '*/.git/*' -not -path "$ROOT/vendor/*" \
+               -not -path "$ROOT/.crush/*")
   fi
 )