feat: align chat rendering with CLI and trim frontend load weight

- Merge thinking and assistant text into one assistant bubble with ordered blocks

- Restyle tool execution blocks to match CLI layout and status

- Remove startup splash screen and ship woff2-only fonts in public

- Add default avatars when agent or user image is unset

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

frontend/src/components/chat/MessageList.module.css

@@ -206,16 +206,11 @@
   flex: 1;
   min-width: 0;
   max-width: 100%;
-  font-size: 16px;
-  line-height: 1.46;
-  color: #666;
   padding: 0;
   margin: 0;
-  overflow: hidden;
-  background: #fff;
-  border: 1px solid #e8ecf0;
-  border-radius: 14px 14px 14px 4px;
-  box-shadow: 0 1px 2px rgba(15, 23, 42, 0.04);
+  background: transparent;
+  border: none;
+  box-shadow: none;
 }
 
 .thinking {