Cluster of priority features and completing some unfinished projects

This project aims to finalize stalled pull requests and implement high-priority features in the Zulip web application, focusing on messaging, search, settings, and backend performance. In messaging and compose UI, the project aims to enable collaborative message editing, allow seamless messaging to unsubscribed channels with proper warning banners, and fix UI jitter during channel subscriptions. In search and settings, the project introduces wildcard, topic, and group-user mentions, revamps alert word notifications to integrate with topic-following, and adds Markdown support to custom profile fields. Finally, it optimizes backend performance by significantly reducing database queries for direct messages, stabilizing password reset email flows, and cleaning up legacy bot configuration logic.