feat: add YouTube thumbnail to README with explainer image below

Author: teycir

README.md

@@ -11,6 +11,10 @@
 
 ![TimeSeal Demo](public/demo.gif)
 
+![YouTube Thumbnail](public/thumbnail.png)
+
+![Time-Seal Architecture](public/explainerimage.png)
+
 ![Time-Seal Animation](public/timeseal_ascii.svg)
 
 ![Time-Seal Landing Page](public/landingpage.png)
@@ -29,8 +33,6 @@
 
 **⚠️ Retention Policy:** All seals are automatically deleted 30 days after their unlock time to protect database resources. Maximum seal lifetime is 60 days (30 days until unlock + 30 days retention).
 
-![Time-Seal Architecture](public/explainerimage.png)
-
 ### Why is this different?
 
 > most "future message" apps contain "trust me bro" promises. Time-Seal is **Cryptographically Enforced** at the Edge.