feat(session): maintain canonical task state

shared/hooks/scripts/show-session-state-pointer.sh

@@ -1,4 +1,4 @@
 #!/usr/bin/env bash
 set -euo pipefail
-root=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/../.." && pwd)
-[ -f "$root/.ai-session/state.json" ] && printf 'Task state is available in .ai-session/state.json; read it only if needed.\n'
+script_dir=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
+python3 "$script_dir/session-state.py" --hook