Fix user message overflow detection on share page

Replace CSS line-clamp with max-height to enable proper overflow detection.
The createOverflow function uses scrollHeight > clientHeight to detect when
content overflows, but line-clamp doesn't create scrollable overflow.
This caused expand button to never appear for truncated user messages.

Changes:
- Replace -webkit-line-clamp:3 with max-height: calc(1.5em * 3)
- Update expanded state to use max-height: none and overflow: visible

Note: This fix is targeted specifically to user messages on share page.

Author: ahosker

packages/web/src/components/share/content-text.module.css

@@ -21,14 +21,12 @@
     line-height: 1.5;
     white-space: pre-wrap;
     overflow-wrap: anywhere;
-    display: -webkit-box;
-    -webkit-box-orient: vertical;
-    -webkit-line-clamp: 3;
-    line-clamp: 3;
+    max-height: calc(1.5em * 3); /* 3 lines at 1.5 line-height */
     overflow: hidden;
 
     [data-expanded] & {
-      display: block;
+      max-height: none;
+      overflow: visible;
     }
   }