- test/test-abstraction-ssp.sh script minor improvement

- result change reflects content corrections: name spelling & a markup
  error, document abstracton, ssp verified ok (may be considered a test)

(assisted by Claude-Code)

test/test-abstraction-ssp.sh: shell script that generates
.ssp files for all sample documents and diffs against
committed reference files in test/reference/abstraction/.

Usage:
  ./test/test-abstraction-ssp.sh --generate ./bin/spine-ldc
  ./test/test-abstraction-ssp.sh ./bin/spine-ldc

Exits 0 if all .ssp files match, 1 if differences found.
Reports changed, missing, and new files.

test/reference/abstraction/: 35 reference .ssp files
generated from the current abstraction, covering all
sample documents including 9-language live-manual.

Co-Authored-By: Anthropic Claude Opus 4.6 (1M context)