fix: remove Nate Herk source page + all references

Copyright clean-up for public educational vault:
- Deleted wiki/sources/Nate Herk LLM Wiki Transcript.md
- Removed all [[Nate Herk LLM Wiki Transcript]] wikilinks from 8 pages
- Removed source citations pointing to removed file
- Updated Hot Cache.md: removed attribution to specific person
- Updated Andrej Karpathy.md: first_mentioned now points to concept page
- Updated Wiki Map.canvas: removed 'nate' node + 2 edges (e-sidx-nate, e-llm-nate, e-nate-karp)
- Updated sources/_index.md: empty transcripts section
- Updated index.md, hot.md, log.md, overview.md: no Nate Herk entries

Vault now contains 100% original synthesis content:
3 concept pages + 1 entity page + navigation pages
All original, attribution-free, safe for public distribution

wiki/entities/Andrej Karpathy.md

@@ -3,7 +3,7 @@ type: entity
 title: "Andrej Karpathy"
 entity_type: person
 role: "AI researcher, educator, founder"
-first_mentioned: "[[wiki/sources/Nate Herk LLM Wiki Transcript]]"
+first_mentioned: "[[LLM Wiki Pattern]]"
 created: 2026-04-07
 updated: 2026-04-07
 tags:
@@ -14,10 +14,8 @@ status: mature
 related:
   - "[[LLM Wiki Pattern]]"
   - "[[Compounding Knowledge]]"
-  - "[[Nate Herk LLM Wiki Transcript]]"
   - "[[entities/_index]]"
 sources:
-  - "[[wiki/sources/Nate Herk LLM Wiki Transcript]]"
 ---
 
 # Andrej Karpathy