fix(web): patch assistant-ui tap scheduler for bulk history prepends

Loading an older page prepends hundreds of messages in one flush. tap's
scheduler aborts after 50 dirty resources and drops the overflow, so the
thread never applied the merged page: the scroll-restore gate never
passed and the top sentinel kept re-triggering (loads everything at
once). Raise MAX_FLUSH_LIMIT 50->2000 via bun patchedDependencies.

Adds a Playwright regression spec driving the real message-window store
and HappyThread against a fake paginated API: one page per top
approach, scroll restored, no idle reloads.

package.json

@@ -37,5 +37,8 @@
         "playwright": "1.60.0",
         "react-devtools-core": "^7.0.1",
         "vite-plugin-pwa": "^1.2.0"
+    },
+    "patchedDependencies": {
+        "@assistant-ui/tap@0.3.5": "patches/@assistant-ui%2Ftap@0.3.5.patch"
     }
 }