spec-spine: Hook for Claude Code

{
  "Stop": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "cd \"${CLAUDE_PROJECT_DIR:-.}\" 2>/dev/null || exit 0\n[ -d specs ] || exit 0\n# Resolve the spec-spine binary for the repository this hook acts on:\n# $SPEC_SPINE_BIN, then that repository's own release build, then PATH. A repo\n# that builds its own binary must be governed by the one it builds; the PATH\n# fallback keeps an adopter on the published CLI working (spec 093).\nspec_spine_bin() {\n  if [ -n \"${SPEC_SPINE_BIN:-}\" ] && [ -x \"${SPEC_SPINE_BIN}\" ]; then echo \"${SPEC_SPINE_BIN}\"; return 0; fi\n  if [ -x \"$1/target/release/spec-spine\" ]; then echo \"$1/target/release/spec-spine\"; return 0; fi\n  command -v spec-spine 2>/dev/null\n}\n# Spec 123: an in-tree build older than the source it is built from was built\n# from an earlier revision, and its verdict is that revision's reading of this\n# corpus. Prints the first input newer than the binary, or nothing. Only the\n# repository's own build has inputs here to compare against, so an override or\n# a PATH binary prints nothing and is named instead. Reads mtimes; never builds.\nspec_spine_reader_predates() {\n  [ \"$1\" = \"$2/target/release/spec-spine\" ] || return 0\n  # The inputs are the files cargo compiled into this binary, from the dep-info\n  # it rewrites on every link, so a change the binary does not depend on (a\n  # test, a fixture, a manifest's dev table) never ages it, and the rebuild\n  # this names always clears what it reports. Without that record, the source\n  # and embedded-schema trees stand in for it.\n  # Read line by line (no word splitting, no globbing), and trust only listed\n  # files that exist inside this repository: a record naming another\n  # checkout's files (a copied or moved build) says nothing about this one, so\n  # it falls through to the fallback rather than reading as \"not older\".\n  if [ -f \"$1.d\" ]; then\n    r=$(sed 's/^[^:]*://' \"$1.d\"