feat: instant sync — push on write, pull on reconnect, render from cache

- Add kick-ch to SyncedAtom: swap!/reset! trigger immediate push
  instead of waiting for the 15s sync loop interval
- SSE: pull on reconnect ("connected" message), not just on new events,
  so coming back online picks up missed server changes
- TodoMVC: render and bind events before IDB load completes; the watch
  re-renders automatically when cached data arrives

example/todomvc/pocketbook/todomvc.cljs

@@ -247,18 +247,16 @@
                    :interval 15000})]
       (reset! !conn conn)
       (reset! !todos todos)
-      ;; Wait for IDB load
-      (<! (pb/ready? todos))
-      ;; Initial render
+      ;; Render + bind immediately (empty or stale is fine)
       (render!)
       (bind-events!)
-      ;; Re-render on any data change
+      ;; Re-render on any data change (fires when IDB loads + server syncs)
       (add-watch todos :render (fn [_ _ _ _] (render!)))
-      ;; Re-render on filter change
       (add-watch !filter :render (fn [_ _ _ _] (render!)))
-      ;; Online/offline status updates
       (.addEventListener js/window "online" (fn [_] (render!)))
       (.addEventListener js/window "offline" (fn [_] (render!)))
+      ;; Wait for IDB — watch triggers render automatically
+      (<! (pb/ready? todos))
       (js/console.log "🔶 Pocketbook TodoMVC loaded —" (count @todos) "todos"))))
 
 (init)