Add lectures folder with ethereum-crypto-2026 structure

Co-authored-by: han <han@noreply.fbrns.co>

README.md

@@ -14,8 +14,13 @@ Study system combining:
 - **graph-theory/** — Graphs, trees, algorithms
 - **algorithms/** — Complexity, sorting, searching
 - **cryptography-prep/** — Building blocks for crypto (once foundation is solid)
+- **lectures/** — Course-specific lecture notes (see below)
 - **lecture-notes/** — Raw notes from lectures before organizing
 
+## Lectures
+
+- [Ethereum Cryptography 2026](./lectures/ethereum-crypto-2026/) — EPF course
+
 ## Study Flow
 
 1. Watch lecture → save raw notes to `lecture-notes/`