Family Chat (2.0): a built-in messenger for the family, phase 1

- Chat tab: direct chats and groups, text, attachments, replies, reactions, edit and delete, unread counts, search, drafts, mute and archive
- Live delivery over server-sent events; phone push for people who are not in the app (muted chats stay quiet)
- chat.js keeps conversations and files in data/chat; push.notify sends one person a notification
- Roadmap updated: phase 1 done, combined inbox with Signal still to do

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

public/index.html

@@ -92,6 +92,7 @@
 <script src="/sheets.js"></script>
 <script src="/file-actions.js"></script>
 <script src="/signal-view.js"></script>
+<script src="/chat-view.js"></script>
 <script src="/mail.js"></script>
 <script src="/share.js"></script>
 <script src="/cast.js"></script>