phase 7: Mycelium — persistent knowledge network connecting runs

- Mycelium graph: nodes/edges/strength, deposit discoveries, weighted extraction
- Fungal nodes: ECS entities on world map with bioluminescent glow animation
- Knowledge system: deposit at nodes (+ auto on death), memory flash retrieval
- Mycosis: visual tint overlay on prolonged node contact, reveal threshold
- Spore shop: 5 Cradle bonuses (health, elements, knowledge boost)
- MetaState extended with MyceliumGraphData, IndexedDB persistence updated
- GameScene: node spawning, glow rendering, E-key interaction, mycosis overlay
- CradleScene: spore shop UI, Mycelium stats, purchased effects forwarding
- 36 new tests (385 total)

Co-authored-by: Cursor <cursoragent@cursor.com>

src/run/types.ts

@@ -130,6 +130,44 @@ export interface MetaState {
   bestRunDiscoveries: number;
   /** Run history summaries */
   runHistory: RunSummary[];
+  /** Mycelium knowledge graph (persistent between runs) */
+  mycelium: MyceliumGraphData;
+}
+
+/** Serializable Mycelium graph data (stored in MetaState) */
+export interface MyceliumGraphData {
+  /** Knowledge nodes */
+  nodes: MyceliumNodeData[];
+  /** Connections between nodes */
+  edges: MyceliumEdgeData[];
+  /** Total deposits across all runs */
+  totalDeposits: number;
+  /** Total extractions across all runs */
+  totalExtractions: number;
+}
+
+/** A knowledge node in the persistent Mycelium graph */
+export interface MyceliumNodeData {
+  /** Unique node ID (format: "type:id", e.g. "element:Na") */
+  id: string;
+  /** Knowledge category */
+  type: 'element' | 'reaction' | 'compound' | 'creature';
+  /** Reference to the specific knowledge item */
+  knowledgeId: string;
+  /** Run on which this was first deposited */
+  depositedOnRun: number;
+  /** Knowledge strength 0–1 (increases with repeated deposits) */
+  strength: number;
+}
+
+/** An edge connecting two knowledge nodes in the Mycelium */
+export interface MyceliumEdgeData {
+  /** Source node ID */
+  from: string;
+  /** Target node ID */
+  to: string;
+  /** Connection strength 0–1 */
+  weight: number;
 }
 
 export interface RunSummary {