fix: Prevent long unbroken strings from overflowing message bubbles

Add overflow-wrap: break-word to .message-content so SHA256 hashes
and similar strings wrap within the bubble boundary.

src/generator.ts

@@ -779,6 +779,7 @@ function generateCss(theme: Theme, hasMultipleScenarios: boolean, colors?: Color
       position: relative;
       line-height: 1.6;
       box-shadow: var(--shadow-sm);
+      overflow-wrap: break-word;
     }
     
     /* Add subtle tails */