[TUNER88]

Recovers #19. That PR was closed unmerged when its base branch data/sounds-json was deleted after #18 merged. This is the same two commits, cherry-picked onto current master, with no content changes.

• scripts/generate_readme.py writes the new sections from data/, between <!-- BEGIN GENERATED … --> / <!-- END GENERATED --> markers right after the iOS 7.0.2 list. It also adds 4 TOC lines.
• New sections:
  • SystemSoundIDs added after iOS 7 (293 rows)
  • List of all system audio files in iOS 26
  • List of all system audio files in iOS 27
  • Changes since iOS 7
• data.yml gains a step that runs generate_readme.py --check.

This is additions only. Verified against master:

• 0 removed or changed lines.
• The ID table (125 rows) and the iOS 7.0.2 list are byte-identical.
• All 22 existing headings and anchors are present, with no duplicates.
• scripts/check_must_not_break.py --online passes.