Carry conversations into new sessions with a visible summary

- Bots get continue_in_new_session: the bot writes a title and summary,
  the session closes for good (read-only) and the new one opens with the
  summary as a "Carried over from the last session" message that links
  back to the old session.
- Continue in new session (conversation menu, sessions modal) and the
  automatic rollover at the session length do the same; New session now
  starts a fresh, unlinked session.
- Session length is an app setting in Settings > General.
- ?session_id= opens a session; a carried-over one shows a bar linking to
  where the conversation went on instead of the composer.
- The thread can open the previous session above the current one (shown
  only, never in the prompt), and replies get search_past_sessions and
  read_past_session.
- Sessions are named from their opening messages, not their latest, and
  a carried summary is labelled as the earlier session's.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/bots/[bot_id]/(partials)/carried-over-chip.tsx

@@ -0,0 +1,35 @@
+import { History } from "lucide-react";
+import Button from "@moduletrace/twui/layout/Button";
+import conversationHref from "@/src/utils/conversation-href";
+
+type Props = {
+    bot_id: number | string;
+    workspace_id?: number | string | null;
+    /**
+     * The session the summary carries on from.
+     */
+    session_id: number | string;
+};
+
+/**
+ * Heads the summary that opens a session the bot moved the conversation
+ * into (`continue_in_new_session`), and opens the session it carries on
+ * from to read. The thread's "Show the previous session" shows the same
+ * messages in place; this is the other way there, on purpose.
+ */
+export default function CarriedOverChip({ bot_id, workspace_id, session_id }: Props) {
+    return (
+        <Button
+            type="button"
+            variant="outlined"
+            color="gray"
+            size="smaller"
+            title="Open the session this one carries on from"
+            href={conversationHref({ bot_id, workspace_id, session_id })}
+            beforeIcon={<History size={14} aria-hidden className="shrink-0" />}
+            className="inline-flex h-6 gap-1.5! flex-nowrap align-middle px-2! text-[11px] font-bold whitespace-nowrap text-ink dark:text-ink bg-transparent hover:bg-sunken"
+        >
+            Carried over from the last session
+        </Button>
+    );
+}