fix(dashboard): sort chat session switcher by most-recent activity (#49104)

The Chat-tab session switcher rendered rows in the API's default
order="created" (original start time) while each row displays
last_active — so a session you just messaged in could sit below an
older one, and the list looked unsorted against its own timestamps.

Pass order="recent" from ChatSessionList so the switcher sorts by
latest activity across the compression chain (most-recently-used at
top, ChatGPT-style; long conversations that auto-compressed into a new
continuation id stay on the first page). Adds an optional, defaulted
`order` arg to api.getSessions; the paginated Sessions page keeps the
stable created order.

web/src/components/ChatSessionList.tsx

@@ -85,7 +85,7 @@ export function ChatSessionList({
     setLoading(true);
     setError(null);
     api
-      .getSessions(SESSION_LIMIT, 0, scopeKey)
+      .getSessions(SESSION_LIMIT, 0, scopeKey, "recent")
       .then((res) => {
         if (reqRef.current !== myReq) return;
         setSessions(res.sessions);

web/src/lib/api.ts

@@ -344,9 +344,17 @@ export const api = {
       window.location.assign("/login");
       return r;
     }),
-  getSessions: (limit = 20, offset = 0, profile = getManagementProfile()) =>
+  getSessions: (
+    limit = 20,
+    offset = 0,
+    profile = getManagementProfile(),
+    order: "created" | "recent" = "created",
+  ) =>
     fetchJSON<PaginatedSessions>(
-      appendProfileParam(`/api/sessions?limit=${limit}&offset=${offset}`, profile),
+      appendProfileParam(
+        `/api/sessions?limit=${limit}&offset=${offset}&order=${order}`,
+        profile,
+      ),
     ),
   getSessionMessages: (id: string, profile = getManagementProfile()) =>
     fetchJSON<SessionMessagesResponse>(