Add sourced AI copyright and music-case pages

[itsmeront]

Summary

• Add draft knowledge pages for generative-AI copyright and litigation, including Thaler, Bartz, Kadrey, Ross, Times v. OpenAI, Spyder, Garcia, and a brain-rot topic, cited from primary court and agency records.
• Add the music-industry cluster: UMG v. Suno, UMG/Sony v. Udio (including the 2026 follow-on complaint), Concord v. Anthropic, and the non-final German GEMA v. OpenAI judgment, with a hub topic that keeps sound recordings separate from lyrics.
• Regenerate indexes so the handbook, relationships, and retrieval set include the new pages.

Test plan

• Open TOPIC-AI-COPYRIGHT, TOPIC-AI-LITIGATION, and TOPIC-AI-MUSIC-COPYRIGHT and confirm case links resolve.
• Spot-check CASE-UMG-V-SUNO, CASE-UMG-V-UDIO, CASE-CONCORD-V-ANTHROPIC, and CASE-GEMA-V-OPENAI footnotes against the linked SRC records.
• Confirm draft status and research-debt notes do not treat pending allegations or the German first-instance judgment as settled U.S. law.
• Run python tools/validate_metadata.py and python tools/validate_links.py.