refactor(ui): remove defaults from MessageCard config props

max_title_size and max_message_size must now be passed explicitly
from board configuration - no more fallback defaults.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: mkg20001

ui/src/components/conversation.rs

@@ -1219,10 +1219,8 @@ pub fn MessageCard(
     #[props(default)]
     default_reply_to: Option<ReplyContext>,
     /// Maximum title length (from board configuration)
-    #[props(default = 100)]
     max_title_size: usize,
     /// Maximum message length (from board configuration)
-    #[props(default = 10000)]
     max_message_size: usize,
 ) -> Element {
     let msg = message.clone();