fix: normalize Windows CRLF line endings in clipboard text (#20283)

On Windows, clipboard text uses CRLF (\r\n) line endings which can cause newlines to be lost or displayed incorrectly when pasted via the {{CLIPBOARD}} variable.

Fixed by converting CRLF to LF before inserting clipboard text.

Fixes #19370

src/lib/components/channel/MessageInput.svelte

@@ -126,7 +126,7 @@
 				}
 			}
 
-			text = text.replaceAll('{{CLIPBOARD}}', clipboardText);
+			text = text.replaceAll('{{CLIPBOARD}}', clipboardText.replaceAll('\r\n', '\n'));
 		}
 
 		if (text.includes('{{USER_LOCATION}}')) {