event-model, client-core, transcript-ui: carry main's LimitReached event

The merge that brought main into rustify added Event::LimitReached to the
server's drivers, but on this branch the enum lives in event-model, which
the merge left without it, so ai-server (and ui-sandbox.sh) did not build.
Definition copied from main's driver.rs; the fold mirrors TranscriptItems.kt's
LimitNote; the iris row shows the epoch until P1 brings a time formatter.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

client-core/src/transcript_fold.rs

@@ -112,6 +112,13 @@ pub enum TranscriptItem {
     ClearedNote {
         seq: u64,
     },
+    /// The account's usage limit stopped the turn; `resets_at` is epoch
+    /// seconds when the dialect said when it lifts (`LimitNote` in
+    /// `TranscriptItems.kt`).
+    LimitNote {
+        seq: u64,
+        resets_at: Option<f64>,
+    },
     CompactedNote {
         seq: u64,
         pre_tokens: Option<u64>,
@@ -131,6 +138,7 @@ impl TranscriptItem {
             | Self::CommandRow { seq, .. }
             | Self::Note { seq, .. }
             | Self::ClearedNote { seq }
+            | Self::LimitNote { seq, .. }
             | Self::CompactedNote { seq, .. } => *seq,
             Self::QuestionCard(card) => card.seq,
         }
@@ -525,6 +533,14 @@ pub fn fold_event(items: &[TranscriptItem], entry: &SeqEvent) -> Vec<TranscriptI
             items.push(TranscriptItem::ClearedNote { seq });
             items
         }
+        Event::LimitReached { resets_at } => {
+            let mut items = items.to_vec();
+            items.push(TranscriptItem::LimitNote {
+                seq,
+                resets_at: *resets_at,
+            });
+            items
+        }
         Event::Compacted {
             pre_tokens,
             post_tokens,