Real-Time Chat App

Build a real-time team chat app with the following features:

**Workspaces:**
- Sign up creates a personal workspace; invite teammates by email
- Users can belong to multiple workspaces and switch via a sidebar

**Channels:**
- Public channels (anyone in workspace can join), private channels (invite-only)
- Channel sidebar grouped: Channels, Direct Messages, Threads
- Create channel with name, description, and visibility
- Channel detail: message stream newest-at-bottom, typing indicator, online dots next to active members

**Messages:**
- Real-time message stream using Supabase Realtime
- Message actions: reply in thread, react with emoji, edit (within 15 min), delete
- @mentions notify the tagged user (in-app bell badge + optional email via Resend)
- Slash commands: /me, /giphy, /shrug, /remind

**Threads:**
- Any message can spawn a thread; threads open in a right-hand drawer
- Thread participants get follow-up notifications

**Files:**
- Drag-and-drop upload to the message composer
- Image previews inline, other files as attachments
- Stored in Supabase Storage

**Search:**
- Search across all channels the user has access to
- Filter by channel, person, date range

**Design:**
- Three-pane layout: workspace switcher / channel sidebar / message stream
- Dark mode by default (chat apps live in dark mode)
- Compact, high-density typography
- Mobile: single pane that slides between views

Store everything in Supabase. Use Supabase Realtime for message delivery and presence. RLS so private channels are invisible to non-members.