Replace the floating chat FAB/window with a first-class Chat tab under
Inbox, laid out as an IM-style two-pane surface (thread list + conversation).
Highlights:
- New Chat page (packages/views/chat/chat-page.tsx) with URL-addressable
session selection; web + desktop routing wired up. Removes the old
chat-fab / chat-window / resize-handles / context-items paths.
- IM thread list: agent avatar + last-message preview + IM timestamp, red
unread *count* badge (read-cursor model), presence-gated typing vs waiting.
Rename lives only in the conversation header ⋯ menu (not the list hover).
- Per-session conversation header (rename / view agent / delete), agent-aware
empty state (avatar + name + description + starter prompts), and a
deterministic clean-title derivation from the first message.
- Server: read-cursor unread model (migration 145) and per-user pinned agents
(migration 146, dedicated chat_pinned_agent table + handler/queries).
New-agent welcome chat auto-enqueues a real agent run (LLM intro, no
static template).
- Design: fade the global --border token; borderless list headers on
Chat/Inbox, kept (faded) on the conversation header.
Verified: pnpm typecheck (all packages), go build ./..., go vet, gofmt.
Co-authored-by: multica-agent <github@multica.ai>
