Name sessions with the model and keep the rail list live

Sessions no longer take their title from the first message: once the first exchange is sent, the text model writes the title and summary, which the rail and sessions list show. The summary records how many messages it covers so a stale one is rewritten before it is carried into the next session.

The sessions hook now reloads on live message and session events, so a session started by the first message, a rollover or another tab appears without a reload. New sessions are pushed as server:bot-session, both from the process that changed them and through the live relay.

src/data/app-data.ts

@@ -238,6 +238,12 @@ export const AppData = {
      */
     BotSessionSummaryMessages: 80,
     BotSessionSummaryMaxChars: 4000,
+    /**
+     * The first messages of a session the bot reads to name and summarize
+     * it once the first reply is in, and how long its title may be.
+     */
+    BotSessionNameMessages: 4,
+    BotSessionTitleMaxChars: 80,
     /**
      * Sessions listed per page in a conversation's sessions modal.
      */