fix: use mempalace CLI in hook scripts instead of python3 -m

Hook scripts used `python3 -m mempalace` which fails when mempalace is
installed via pipx or uv. Using the `mempalace` CLI command directly
works for all installation methods. Dev users running from source should
use `pip install -e .` as documented in CONTRIBUTING.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.codex-plugin/hooks/mempal-hook.sh

@@ -3,7 +3,7 @@ set -euo pipefail
 HOOK_NAME="${1:?Usage: mempal-hook.sh <hook-name>}"
 INPUT_FILE=$(mktemp) || { echo "Failed to create temp file" >&2; exit 1; }
 cat > "$INPUT_FILE"
-cat "$INPUT_FILE" | python3 -m mempalace hook run --hook "$HOOK_NAME" --harness codex
+cat "$INPUT_FILE" | mempalace hook run --hook "$HOOK_NAME" --harness codex
 EXIT_CODE=$?
 rm -f "$INPUT_FILE" 2>/dev/null
 exit $EXIT_CODE