feat: Fibonacci spiral canvas + graph filter + domain sub-hubs

- Wiki Map.canvas: 13 nodes at golden angle 137.5deg (Fibonacci/sunflower pattern)
  - index at center, 3 domain _indexes in ring 1, content in outer rings
  - Color coded: orange=concepts, purple=entities, green=sources, blue=navigation
  - 17 semantic edges with labels
- graph.json: search:path:wiki — eliminates all plugin file noise
  - hideUnresolved:true — removes phantom Subject A/B nodes
  - nodeSizeMultiplier 1.8 — hub nodes visually dominant
  - repelStrength 30 — clean radial spreading
- Created wiki/concepts/_index.md, wiki/entities/_index.md, wiki/sources/_index.md
  - These are domain hub nodes that create the 3-ring hierarchy in graph view
- All wiki pages now link to their domain _index
  - Creates proper hub-and-spoke topology in force-directed graph

wiki/concepts/Compounding Knowledge.md

@@ -17,6 +17,7 @@ related:
   - "[[Hot Cache]]"
   - "[[Andrej Karpathy]]"
   - "[[Nate Herk LLM Wiki Transcript]]"
+  - "[[concepts/_index]]"
 sources:
   - "[[wiki/sources/Nate Herk LLM Wiki Transcript]]"
 ---

wiki/concepts/Hot Cache.md

@@ -19,6 +19,7 @@ related:
   - "[[Compounding Knowledge]]"
   - "[[index]]"
   - "[[hot]]"
+  - "[[concepts/_index]]"
 sources:
   - "[[wiki/sources/Nate Herk LLM Wiki Transcript]]"
 ---

wiki/concepts/LLM Wiki Pattern.md

@@ -21,6 +21,7 @@ related:
   - "[[Andrej Karpathy]]"
   - "[[Nate Herk LLM Wiki Transcript]]"
   - "[[index]]"
+  - "[[concepts/_index]]"
 sources:
   - "[[wiki/sources/Nate Herk LLM Wiki Transcript]]"
 ---

wiki/concepts/_index.md

@@ -0,0 +1,34 @@
+---
+type: meta
+title: "Concepts Index"
+updated: 2026-04-07
+tags:
+  - meta
+  - index
+  - concept
+domain: knowledge-management
+status: evergreen
+related:
+  - "[[index]]"
+  - "[[LLM Wiki Pattern]]"
+  - "[[Hot Cache]]"
+  - "[[Compounding Knowledge]]"
+---
+
+# Concepts Index
+
+Navigation: [[index]] | [[entities/_index|Entities]] | [[sources/_index|Sources]]
+
+All concept pages — ideas, patterns, and frameworks extracted from sources.
+
+---
+
+## Knowledge Management
+
+- [[LLM Wiki Pattern]] — the core architecture for persistent, compounding knowledge bases
+- [[Hot Cache]] — ~500-word session context file, updated after every ingest
+- [[Compounding Knowledge]] — why the wiki grows more valuable over time, unlike RAG
+
+---
+
+## Add new concepts here as they are extracted from sources.