In-App Deal Chat

Migration f3a4b5c6d7e8 adds deal_messages:

• Polymorphic: deal_kind VARCHAR(20) (marketplace | scheduling) + deal_id UUID (no FK — points at one of two deal tables)
• Workspace-level read state via read_by JSONB (array of workspace IDs; sub-employees share read state)
• body TEXT, attachments JSONB, edited_at, is_deleted (soft-delete, body surfaces as [deleted])
• Indexes: (deal_kind, deal_id, created_at DESC), (sender_workspace_id, created_at DESC)

• GET /deal-chat/{deal_kind}/{deal_id}/messages?limit&before — paginated history (newest first)
• POST /deal-chat/{deal_kind}/{deal_id}/messages — send (1–4000 chars, up to 5 attachments); fires a grouped notification to the other party (group_key=chat.{deal_kind}.{deal_id}, 60-minute coalesce window)
• POST /deal-chat/{deal_kind}/{deal_id}/messages/mark-read
• GET /deal-chat/{deal_kind}/{deal_id}/unread-count
• GET /deal-chat/unread-summary — one row per deal with unread messages (used by deals-list unread dots)
• PATCH /deal-chat/messages/{id} — edit own message (15-minute window)
• DELETE /deal-chat/messages/{id} — soft delete (sender or SA)
• POST /deal-chat/{deal_kind}/{deal_id}/attachments/upload — multipart, 10 MB cap

Every endpoint verifies the caller is buyer/seller workspace (or SA).

/notifications/stream now emits two frame types:

• {type: "notification", ...} — unchanged from before
• {type: "chat_message", deal_kind, deal_id, message} — new; only for threads the caller is party to

The NotificationBell component listens for chat frames and dispatches CustomEvent('adnet:chat_message') on window. DealChatPanel subscribes to that event to append messages and auto-mark-read when the panel is open.

• components/chat/DealChatPanel.tsx — reusable drawer with bubble UI, own-vs-other styling, inline image previews, file chips, 15-minute edit/delete menus, 5-attachment composer (Enter=send, Shift+Enter=newline), optimistic pending messages with spinner + rollback, auto-scroll when near bottom, infinite scroll up via before cursor, 12s polling fallback when SSE is unavailable
• Deal detail (/marketplace/deals/[id]): header Chat button with unread badge
• Opportunities deal modal (/opportunities → DealDetailModal): same Chat button (dealKind='scheduling')
• Unread dots: orange dot on /marketplace/deals rows and on opportunities My Deals / Influencer Deals tables for deals with unread messages

• ADV → SRC message delivery, SSE push, unread badges, mark-read, edit/delete, attachments
• Existing notification flows unaffected (bell, SSE, digest email)
• Existing deal flows unaffected (content share, payment, proof, dispute, revisions)

• Typing indicator
• Per-user fine-grained read receipts (currently workspace-level only)
• Dedicated CHAT NotificationCategory — reuses INFLUENCER to avoid enum migration on existing preference rows

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